At the start of Episode 20 ("Nothing Personal"), we see Agent Maria Hill walk
down the steps of the U.S. Department of Justice building, in Washington, D.C.
As she walks, she talks on the phone about how she's being followed,
and notes the various people who are shadowing her..
No, this isn't really Washington, D.C.
This is actually a church in Pasadena, California, which just happens to have
the same kind of Greek revival architecture as the buildings in D.C.
It's the First Church of Christ Scientist,
at 80 S. Oakland Avenue, in Pasadena.
(In the screencap above, the camera is looking east.)
Here is a matching StreetView of that church.
And just for the record, here is what the real Dept. of Justice looks like:
When she looks across the street at a fake homeless man pushing a shopping cart,
she isn't looking west across Oakland Avenue, as it might seem.
Instead, they shot that scene with the camera actually looking north
at a building across Green Street, which houses
"Le Cordon Bleu College of Culinary Arts".
Here is a matching StreetView of that building.
And when Agent Hillin ducks into an alleyway and encounters Melinda May...
She is in Converse Alley, around 35 S. Oakland Ave, off the east side of
Oakland Ave, Pasadena, a block north of the "Dept. of Justice" church.
(The camera is looking north/northwest in the screencap above.)
Here is a matching StreetView of the alley.