I thought I recognized those giant light fixtures -- it's outside the City Post Office Building, now called the Postal Square Building. This is at Massachusetts Avenue and North Capitol Street, looking north along North Capitol. Here is how one of the lights looks today:
There don't seem to be many pictures of that side of the building online, but here's a shot from 1998. If you look closely you can see the rounded corner to the steps:
The National Postal Museum is in this building now, among other things.
