The Cooper Union is a college in Manhattan, established in 1859 for education in engineering, the arts and architecture for any candidate, regardless of race, religion, sex, wealth or social status. Pretty forward thinking for 1859, of course. And even more impressive: from the day it first opened until 2013 anbody admitted got a full scholarship. The economic downturn put an end to that.
The Union plays a role in The Gilded Hour, but primarily in the backstory and in a very brief flashback. Two of the primary characters meet as children when their parents attend Abraham Lincoln’s speech at the Cooper Union in October of 1860.
The map (click for the full size) is of a small part of Manhattan in 1880, which happens to contain the Savard residence (marked with a “1”), the Cooper Union, Washington Square Park and a number of other places relevant to the story. The photo on the left is taken looking north from th esmall park behind the Union in about 1875, just before the elevated trains went up on Third and Fourth Avenues. The photo on the right is a little later, and you can see that train passengers had a good view into the classrooms as they sped on by.