During the planning of the Croton Aqueduct in the 1830s, there was much debate over how the aqueduct should cross the Harlem River into Manhattan. There were three main alternatives being considered: a tunnel beneath the river; a low embankment crossing with a short arch span; and a substantial, high-level bridge. John B. Jervis, the chief engineer, favored the embankment and low bridge, as it would be the cheapest and easiest to build of the options. Many others, however, felt that this crossing should exude a grandeur befitting the monumental nature of the aqueduct.
Thanks to the timely heroics of our friend Lewis G. Morris, the State Legislature intervened in the process, passing a law that prohibited the new crossing from hindering ship traffic on the river, thus eliminating the embankment alternative from contention. Fearing uncertain, escalating construction costs, Jervis ruled out the tunnel option as well. And so it was decided that a stately series of high stone arches would carry the Croton water across the Harlem River in style.
The High Bridge finally opened in 1848, six years after the aqueduct, which used a temporary inverted siphon to cross the Harlem in the meantime. If you remember how to view those "Magic Eye" images, check out this stereograph of the bridge from 1859. After a pedestrian walkway was added on top of the bridge, well-attired promenaders would come from miles around to bask in the majestic views from high above the river.
While the aqueduct itself used only the force of gravity to deliver water to the city, pumping was necessary to fill the water tower visible in the photo above, along with a reservoir located near its base. The tower and reservoir were completed by 1872, providing the increased hydraulic head needed to serve the higher altitudes of Upper Manhattan.
Eventually a tunnel was drilled beneath the river, replacing the High Bridge as the conveyor of Croton water to Manhattan. In the 1920s, there was talk of demolishing the bridge, as its archways were proving too narrow for large ships to pass through. This proposal stirred protests among many, with Scientific American declaring that the bridge's destruction would constitute "an act of vandalism . . . without a precedent in the history of our country." A compromise was ultimately reached, and five of the masonry arches were replaced with the single steel span pictured above, improving navigation on the river while still preserving some of the bridge's original character. The High Bridge is generally claimed to be New York's oldest surviving bridge, but, as you now know, that's only partially true.
The pedestrian walkway was closed sometime in the 1960s or '70s, supposedly in response to people using it to throw things at boats passing below. The bridge has been left to deteriorate in the decades since, but, at long last, work is now underway to rehabilitate it and open it to pedestrians once again, albeit with an obnoxiously high safety fence obstructing the views.