These are the so-called "Exorcist Stairs" used in the film The Exorcist that was based here in DC where I live.
There is no house to the left (Where the Priest leaps out the window) only the old Bus system Turn About (Where the buses stopped so Blacks on the bus could move to the back seat as the bus went over the Key Bridge in front of the building, into Virginia where Jim Crow laws were in effect. Today the building is the Spanish Military Embassy office.
The books author, I've forgotten his name, worked as a clerk at nearby Georgetown University and was carrying a report of an actual exorcism in Prince George's County Maryland and stopped at the stairs to sneak a peak of the report, he later included the scene into the film.
Across the street is one of my favorite places in Georgetown, the Tombs. It's been there since 1962. It's part of a local chain called Clyde's. The food is good, the tourist usually don't know about it and it's a relaxing place in the summer when it is over run by Georgetown students.