The building on the lot may cover more land than is within the lot lines. Suppose it encroaches on the highway. The street is either owned by the municipality or else it has an easement to use the street for public purposes. In either event no one has a right to encroach upon it, except by legal permission.1 Such an encroachment if it be by a permanent structure may render the title unmarketable. Likewise the building may encroach upon a neighbor's land. If without his consent, the neighbor may be able, either to recover damages for the encroachment or compel the removal of so much of the building as encroaches on him. A purchaser could not be compelled to accept such a title. The survey also would indicate party walls. It should also be examined with reference to any restriction upon the property; as to whether or not they are violated by the building. The effect of such conditions could be determined only by one familiar with the law applicable in each case.

1 Recent decisions of the supreme court of New York have made it questionable whether the municipal authorities of New York City have authority to grant permission for any encroachment on a public street.