The Metro-North Railroad's Harlem, Hudson and New Haven Lines emerge from a tunnel under Park Avenue at 97th Street, and from 99th through 111th Streets rise along a stone viaduct built in 1871, which then becomes a steel viaduct until the lines cross the Harlem River to the Bronx on the Park Avenue Railroad Bridge.  By 102nd Street, the stone viaduct is tall enough to allow passage of cars and pedestrians from one side of Park Avenue to the other through tunnels. These tunnels are at 105th Street.
<a href="//commons.wikimedia.org/wiki/User:Beyond_My_Ken" title="User:Beyond My Ken">Beyond My Ken</a>
CC BY-SA 4.0
<span class="int-own-work" lang="en">Own work</span>