Opinion by

These appeals are from an order confirming the report of viewers assessing the costs of widening and grading Perrysville avenue in the city of Allegheny. The only question argued is whether the city could assess against the abutting properties a part of the cost of stone walls built at places along the sides of the avenue. A part of the avenue was constructed on the sides of steep hills, and at these places walls were built on the lower side to support the roadway, and on the upper to protect it from banks of earth and stone. Some of these walls were built in part and some of them wholly on the adjoining properties. None, however, were built on the land of the appellants.

The determination of the plan and manner of improving the *539avenue rested with the municipal authorities, and the abutting properties were liable to assessment to the extent to which the local improvement was a permanent benefit to them. If the walls were a necessary part of the street improvement, and the right to maintain them on private property was secured by the city, their cost was properly included in the assessment. The court found that they were necessary for the support and protection of the street, that they were built with the knowledge of the property owners and in most cases at their request or with their express consent, and that the facts disclosed by the testimony estopped the owners to question the right of the city to maintain the walls. In Western Penna. Railway Co. v. Allegheny, 92 Pa. 100, relied on by the appellants, the city assumed the right to locate a retaining wall partly on the property of the railway company, and built it against the company’s protest and assessed the company with the cost thereof. It was held that the building of the wall was without authority, in violation of law and a trespass, and that, since the part built on the company’s property might be removed by it and the part within the line of the street was not self-sustaining and was of no value to the public, no part of the cost could be assessed from the company. In the case before us the city got by consent an easement which it could have obtained by adverse proceedings, and the structure being lawful, necessary and permanent, was properly included in the assessment of benefits.

The order confirming the report of the viewers is affirmed at the cost of the appellants.