In the film, they have to deliver a piano to a house that sits at the top of a steep flight of stairs.
The stairs still exist to this day. They're on N. Vendome St. south of Sunset Blvd. The house to the right still looks pretty much the same.
At the bottom of the stairs you'll find this plaque.
A lady pushing a carriage hits Stan. A toilet was sitting out there on this particular day.