Gautier's Restaurant

[SSlater]

Here's some tight speculation, of the picture:
1. To the far right is a hill top. Capitol Hill?
2. From the tilt of the umbrellas, I'd say we are looking east.
3. Some men are wearing Frock Coats, and some women are wearing Jackets of some kind, and shawls.
4. Notice too, that there is a Band leading this parade.
5. The "long umbrella" looks to be under construction - or at least incomplete.
6. The trees do not have leaves, or at least small ones.
My summary: It is Pennsylvania Ave, in early spring, say April and the windows are draped, commemorating a Death.
PS. The Soldiers are at " Parade Rest". (Relaxed, but in position to move promptly).
("At Ease" The hands are clasped in front, and one foot may be slightly forward, but no talking. "Parade Rest" is a little more casual, notice how the Officers are on their Horses, but not "In Line".
In my opinion, these guys are waiting for the "Parade" to begin."