The City of Philadelphia (Philadelphia) appeals from an April 5, 1993 order of the Court of Common Pleas of Philadelphia County (Common Pleas) which denied Philadelphia’s post-verdict motions and entered judgment in favor of Mary Finn (Finn) in the amount of $203,500. We reverse.
Finn’s complaint averred the following facts. On December 24, 1987, Finn was walking on a sidewalk which adjoined real property on Wood Street owned by Philadelphia. She was injured, when she slipped on grease which had accumulated on the sidewalk, lost her balance, fell, and landed on a two-foot-by-three-foot throw rug which covered a portion of the sidewalk. Finn stated that she did not see the grease or the rug before she fell on the sidewalk, because it was dark. The grease had accumulated because cars and trucks regularly parked on the sidewalk and leaked oil. Finn also alleged that the presence of the rug demonstrated that Philadelphia had notice of a dangerous condition on its sidewalk and had tried unsuccessfully to cover the danger by putting the rug over some grease-covered areas of the sidewalk. Philadelphia denied liability for Finn’s injuries and claimed that it did not have actual or constructive notice of a dangerous condition of the sidewalk. Philadelphia also asserted that it is immune from suit under what is commonly referred to as the Political Subdivision Tort Claims Act (Act), 42 Pa.C.S. §§ 8541-8542.
The matter proceeded to a non-jury trial by stipulated facts. Philadelphia moved for summary judgment and agreed that if a finder of fact could find evidence of a defect “of” the sidewalk and find that Philadelphia had constructive notice of that defect, then it would admit liability, with damages fixed in the amount of $203,500. Common Pleas denied Philadelphia’s motion for summary judgment. After the trial on the stipulated facts, Common Pleas ruled in favor of Finn, finding that Finn had presented sufficient evidence for a trier of fact to conclude both that the grease was a defect “of’ the sidewalk and that Philadelphia had constructive notice of this defect. Philadelphia filed a motion for post-trial relief, but Common Pleas denied Philadelphia’s motion and entered judgment in *258favor of Finn for the $203,500 damage figure stipulated by the parties.1 This appeal followed.
Our scope of review of Common Pleas’ decision is limited to a determination of whether constitutional rights have been violated or whether Common Pleas abused its discretion or committed an error of law. Kearney v. City of Philadelphia, 150 Pa.Commonwealth Ct. 517, 616 A.2d 72 (1992), petition for allowance of appeal denied, 534 Pa. 643, 626 A.2d 1160 (1993). The only issue Philadelphia raises on appeal is whether Common Pleas committed an error of law when it held that the grease created a dangerous condition of the sidewalk.
The Act, at 42 Pa.C.S. § 8541, provides a general grant of immunity to all local agencies for damages caused by acts of the agency or its employees. The Act, at 42 Pa.C.S. § 8542 also sets out eight limited exceptions to governmental immunity. The exception relevant to the present matter is 42 Pa.C.S. § 8542(b)(7) (the sidewalk exception), which imposes liability on a local agency for “[a] dangerous condition of sidewalks within the rights-of-way owned by the local agency....” (Emphasis added.) The issue for this Court to decide is whether a buildup of oil and grease on a sidewalk can be considered a dangerous condition “of’ the sidewalk.
The facts of the instant matter present a controversy which has been difficult for this Court to resolve in past cases involving the sidewalk exception. This controversy is whether the sidewalk exception should be strictly construed to exempt from immunity only those torts caused by a structural or integral defect of the sidewalk or whether the sidewalk exception also imposes liability for torts caused by the existence of foreign substances such as ice, snow, oil, or grease, which can become attached to the sidewalk to the degree that they are only removable by the application of some affirmative force. We intend to resolve this controversy definitively by our decision in the present matter. In order to do so, however, it *259will be helpful to first review our past decisions in this area of law.
Two cases decided by this Court in 1985, Ambacher v. Penrose, 92 Pa.Commonwealth Ct. 401, 499 A.2d 716 (1985) and Ziccardi v. School District of Philadelphia, 91 Pa.Commonwealth Ct. 595, 498 A.2d 452 (1985), established generally that the sidewalk exception permitted the imposition of liability on a municipality only for structural or integral defects of a sidewalk. In Ziccardi, a student was assaulted on a sidewalk adjoining a school district’s property, and the student’s parents filed suit against the school district. We refused to impose liability on the school district because the student’s injury was not caused by a defect in the sidewalk itself. In Ambacher, a pedestrian who had tripped over a wire fence which had fallen onto a sidewalk filed suit against Philadelphia, alleging that her injury was caused by a defect of the sidewalk. We held in Ambacher that the sidewalk exception only permitted the imposition of liability for structural or integral defects of a sidewalk. We concluded that Philadelphia could not be held liable for Ambacher’s injury, because it was caused by a defect “on” the sidewalk rather than “of’ the sidewalk.
This strict construction of the sidewalk exception prevailed until our decision in Giosa v. School District of Philadelphia, 127 Pa.Commonwealth Ct. 537, 562 A.2d 411 (1989), petition for allowance of appeal denied, 525 Pa. 629, 578 A.2d 416 (1990). In Giosa, the plaintiff, Frank Giosa (Giosa), slipped on a sidewalk adjacent to the school district’s property. Giosa sustained injuries in the fall and sued the school district alleging that his fall was caused by an unsafe accumulation of snow and ice on the sidewalk, which the school district had failed to clear. The school district, relying on Ambacher and Ziccardi, argued that it was immune from suit and that Giosa’s injury did not fall within the sidewalk exception, because it was not caused by a defect in the structural integrity or design of the sidewalk.
In our decision in Giosa, we distinguished Ambacher and Ziccardi and concluded that the sidewalk exception was not *260limited solely to design, construction or internal structural defects of sidewalks. Based on the common law “doctrine of hills and ridges,”2 we surmised that ice and snow could become affixed to the sidewalk to the degree that they could not be detached from the surface without the application of affirmative force, and we concluded that if the ice and snow were affixed in that manner, the ice and snow could be characterized as a dangerous condition “of’ the sidewalk. We held in Giosa that the failure to clear an accumulation of snow and ice from a sidewalk could result in a dangerous condition of the sidewalk, for which liability could be imposed pursuant to the sidewalk exception.
Giosa was the first case that espoused these two new concepts: First, that the sidewalk exception was not limited solely to design, construction or internal defects of a sidewalk; and second, that a foreign substance could become so affixed to the surface of a sidewalk that it could become characterized as a defect of that sidewalk. However, since Giosa, these two concepts have been applied unevenly by this Court, resulting in conflicting precedents. This conflict is evidenced by the differences in recent rulings of this Court in Fitchett v. Southeastern Pennsylvania Transportation Authority, 152 Pa.Commonwealth Ct. 18, 619 A.2d 805 (1992), and Shubert v. Southeastern Pennsylvania Transportation Authority, 155 Pa.Commonwealth Ct. 129, 625 A.2d 102 (1993). These two cases are very similar factually, but we reached substantially different results in them.
In Fitchett, the plaintiff, Ruby Fitchett (Fitchett), alleged that she slipped on an accumulation of grease and debris on a subway concourse located on the Southeastern Pennsylvania Transportation Authority’s (SEPTA) property. Fitchett sustained injuries in the fall and brought an action against SEPTA claiming that SEPTA was liable for her injuries pursuant to Section 8522(b)(4) of the Judicial Code, 42 Pa.C.S. *261§ 8522(b)(4)3 (the real estate exception), which is commonly known as the real estate exception to the sovereign immunity granted to the Commonwealth and its agencies. Common Pleas granted SEPTA’s motion for summary judgment and dismissed Fitchett’s action. Fitchett then appealed to this Court.
On appeal, we affirmed Common Pleas’ decision without making any reference to Giosa’s applicability. Instead, we relied upon our Supreme Court’s decision in Snyder v. Harmon, 522 Pa. 424, 562 A.2d 307 (1989), in which the Supreme Court construed the real estate exception to sovereign immunity. Snyder clearly stated that the critical word in the real estate exception language is “of’ in the phrase “[a] dangerous condition of Commonwealth agency real estate.” The Supreme Court also stated in Snyder that “[t]hese key words indicate that a dangerous condition must derive, originate from or have as its source the Commonwealth realty.” Id. at 433, 562 A.2d at 311 (emphasis added). Based on Snyder, we concluded in Fitchett that since the accumulation of grease and debris could not be said to be a defect of the land itself, SEPTA was not liable for Fitchett’s injuries. We also stated that Fitchett’s claim essentially amounted to a claim against SEPTA for a negligent failure to remove the grease and debris and ruled that such a failure does not fall within one of the exceptions to sovereign immunity set out in 42 Pa.C.S. § 8522(b).
Shubert was decided only six months after Fitchett but reached a different result. In Shubert, the plaintiff, Eleanor Shubert (Shubert), alleged that she slipped on an oily, wet surface on a subway platform located on SEPTA’s property. Shubert sustained injuries in the fall and brought an action *262against SEPTA claiming that SEPTA was liable for her injuries pursuant to the real estate exception to SEPTA’s sovereign immunity. Common Pleas rejected Shubert’s claim and granted summary judgment in favor of SEPTA, because the court concluded that pursuant to Mascaro v. Youth Study Center, 514 Pa. 351, 523 A.2d 1118 (1987),4 Shubert’s claim did not fall within the real estate exception, because the oily spot was not a physical defect emanating from the sidewalk. Shubert then appealed to this Court.
On appeal, we reversed Common Pleas’ decision and held that Shubert’s complaint presented a question of fact as to whether the oily spot was affixed to the subway platform so as to become a dangerous condition of the platform. We reached this decision by concluding that although Giosa dealt with an exception to governmental immunity, Giosa was still applicable to Shubert, which involved the real estate exception to sovereign immunity, because our Supreme Court had utilized the same criteria to analyze both exceptions to immunity in Snyder. Common Pleas’ grant of summary judgment was reversed and Shubert’s action was permitted to proceed to trial.
In the present matter, the parties agree that the conflict between the Fitchett and Shubert decisions has created two distinct lines of cases. However, the parties disagree as to which line of cases should apply to the present matter. Finn contends that Giosa and Shubert are applicable in the present matter and that Common Pleas acted properly in following these precedents and denying Philadelphia’s motion for summary judgment. Conversely, Philadelphia takes the position that Giosa and Shubert were wrongly decided and that the present matter should be controlled both by our Supreme Court’s decision in Snyder and this Court’s decision in Fitchett. After carefully considering the arguments presented by *263both parties and reviewing the language of the sidewalk exception, we must agree with Philadelphia’s position.
Giosa and Shubert are problematic decisions, because they essentially impose liability on government entities for a negligent failure to remove a foreign substance from either a sidewalk or real property owned by the government entity. We believe that the language of both the sidewalk exception to governmental immunity and the real estate exception to sovereign immunity indicates that the General Assembly did not intend to impose liability in instances where an injury is caused solely by the presence of a foreign substance on top of the sidewalk or the real property. Moreover, both Giosa and Shubert conflict with our Supreme Court’s decisions in Snyder and Mascaro, which state that the dangerous condition must derive, originate from or have as its source the real estate. Accordingly, Giosa and Shubert are expressly overruled by our decision in the instant matter.
Presently, we hold that in cases involving the sidewalk exception to governmental immunity, liability can be imposed on the government entity only if the plaintiffs injury is caused by a defect or a dangerous condition which originates from the sidewalk itself. Such a defect or dangerous condition is limited solely to the negligent design or construction of the sidewalk or to a defect in the internal structural integrity of the sidewalk. Similarly, in cases involving the real estate exception to sovereign immunity, liability can be imposed on the government entity only if the plaintiffs injury is caused by a defect of the real estate itself. We emphasize, however, that the substance or thing which causes the injury need not emanate from the real estate itself. Liability may be imposed on a government entity in instances where the defective design, construction or condition of the real estate itself restílts in an unnatural accumulation of a substance or thing which itself creates the hazardous condition leading to the injury.
This Court will no longer impose liability pursuant to either the sidewalk exception to governmental immunity or *264the real estate exception to sovereign immunity in cases where the plaintiffs injury is not caused by a defect in the sidewalk or the real estate itself. We will not impose liability for injuries caused by a negligent failure of the government entity to remove a foreign substance from the real estate or the sidewalk. Since ice, snow, oil and grease are all foreign substances which can naturally accumulate on the sidewalk or real estate itself, government entities are not liable for injuries caused solely by the presence of these substances on a sidewalk or on real property.
However, we will permit the imposition of liability if there is an allegation and proof that the substance on the sidewalk or other real estate was caused to be on the real estate because of an improper design, construction, deterioration, or inherent defect of the real estate itself. In those cases, the dangerous condition emanates from the real estate itself. Under such circumstances, a jury could find that the dangerous condition derived or originated from and had as its source the realty. This interpretation of the sidewalk and real estate exceptions is consistent with our Supreme Court’s mandate in Snyder and Mascaro, that all exceptions to governmental immunity must be narrowly interpreted given the express legislative intent to insulate political subdivisions from tort liability.5
As applied to the present matter, this interpretation of the sidewalk exception precludes Finn from establishing liability against Philadelphia. Although Common Pleas found Finn’s factual allegations to be true, these facts, as a matter of law, do not support a verdict which imposes liability on Philadelphia. Finn did not allege or prove that the accumulation of grease on the sidewalk was caused by an improper design, construction, deterioration or inherent defect in the sidewalk. Instead, Finn’s complaint clearly establishes that the accumu*265lation of grease on the sidewalk was deposited by cars and trucks which were previously parked there. We conclude that Common Pleas committed an error of law when it found that the grease was a dangerous condition of the sidewalk and held Philadelphia liable for Finn’s injuries.
Accordingly, Common Pleas’ decision is reversed.
ORDER
AND NOW, this 21st day of June, 1994, the order of the Court of Common Pleas of Philadelphia County in the above-captioned matter is reversed.