At the north edge of Riverside Park South, you find the last remaining section of the old West Side Highway, aka the Miller Elevated Highway.
Very probably the first elevated expressway in the world, the old West Side Highway was designed in the 1920s, and opened in stages between the 1929 and 1939. After the WWII, it was extended south to meet the Brooklyn Battery Tunnel. The brain child of Manhattan borough president Julius Miller, original plans also included the tracks of what would become the High Line, and sought to remove "express" traffic from the local streets below in a dramatic, if naive, attempt to alleviate congestion. It faced protest from the beginning: blocking the sun from the street and deafening traffic noise were not a surprise. Sadly, this elevated expressway would go on to be the inspiration for numerous others, including most directly, Boston's old Central Artery.
As befits its age, it was awkwardly designed: it had central entrance and exit ramps, meaning that drivers faced *only* left-hand exits and entrances. To mitigate this, slow traffic was supposed to keep *left*, not right, on the structure. Curves were tight, and speeds slow. Beyond this, it was full of generous design touches, including Art Deco ironwork and ziggurated streetlights.
The highway came to a famous end in 1973. In rough financial straits, the city & state had neglected the structure for years as it fell into worse in worse shape. The structure finally gave way, a section collapsing under the weight of, ironically, a truck on its way to repair another part of the roadway. Between the lack of maintenance & safety defects, the highway was torn down. Replacement attempts, including the underground Westway proposal, were thankfully shot down as New Yorkers began to realize more & more that a city friendly for cars is not a city friendly for people.
A little more in a comment below...