Cutting a two-mile swath through Brooklyn before heading out through the rest of Long Island, the Prospect Expressway serves at the de facto border between Park Slope and the nebulous neighborhood just to its south, which some call the South Slope, others Greenwood Heights.
Looking northeast towards Fifth
The brainchild of (who else?) Robert Moses, it's a deep sunken trench of a highway and was constructed during the 1950s. The top photo was taken from the top of the Grand Prospect Hall (looking southwest), which was situated on a fairly glamorous block when it was first constructed in 1892. How times have changed!