9. The New York and Harlem Railroad Ran Up the Center of Park Avenue
Back when Park Avenue was still called Fourth Avenue in the 1830s, it carried the tracks of the New York and Harlem Railroad. Running from lower Manhattan to above Harlem, this railroad was one of the first in the U.S. as well as the world’s first street railway. While the railroad originally cut through Murray Hill in the 1830s, it was covered with grass from 34th to 40th Street by the 1850s. This space became known as a park, which was why the road was renamed “Park Avenue” in 1860. Eventually the area extended to 42nd Street. When the railroad tracks leading up to 96th street were demolished, Park Avenue spread uptown.