Park Avenue (formerly Fourth Avenue) is a 140 foot wide boulevard that carries north- and southbound traffic in the New York City borough of Manhattan. For most of its length, it runs parallel to Madison Avenue to the west and Lexington Avenue to the east.
The flowers and greenery in the median of Park Avenue are maintained by the Fund for Park Avenue. Begonias are a flower of choice for the Fund's gardeners because there is no automatic watering system and they can cope with the hot sun.
Each December, Christmas trees are placed in the median in a tradition that started in 1945 as a memorial to soldiers killed in action.
The road that becomes Park Avenue originates as the Bowery. From Cooper Square at 8th Street to Union Square at 14th Street, it is known as Fourth Avenue. Above 14th Street, it turns slightly east of north to align with other avenues of the Commissioners' Plan of 1811. From 14th Street to 17th Street, it forms the eastern boundary of Union Square and is known as Union Square East; its southbound lanes merge with Broadway for this distance. From 17th Street to 32nd Street, it is known as Park Avenue South, and above 32nd Street, for the remainder of its distance, it is known as Park Avenue.
Between 33rd Street and 40th Street, the left-hand northbound lane descends into the Murray Hill Tunnel. Immediately across from 40th Street, the center lanes of Park Avenue rise onto an elevated structure that goes around Grand Central Terminal and the MetLife Building (formerly the PanAm Building), carrying each direction of traffic on opposite sides of the buildings. The bridge, one of two structures in Manhattan known as the Park Avenue Viaduct, returns to ground level at 46th Street after going through the Helmsley Building (also referred to as the New York Central Building or 230 Park Avenue). The IRT Lexington Avenue Line runs under this portion of the street. Once the line reaches Grand Central, it shifts east to Lexington Avenue.
As Park Avenue enters Midtown north of Grand Central Terminal, it is distinguished by many glass-box skyscrapers that serve as headquarters for corporations such as JPMorgan Chase at 270 Park Avenue and 277 Park Avenue, UBS at 299 Park Avenue, Citigroup, Colgate-Palmolive, and MetLife at the MetLife Building.
From Grand Central to 97th Street, Metro-North Railroad tracks run in a tunnel underneath Park Avenue (the Park Avenue Tunnel). At 97th, the tracks come above ground, rising onto the other Manhattan structure known as the Park Avenue Viaduct. The first street to pass under the viaduct is 102nd Street; from there to the Harlem River the railroad viaduct runs down the middle of Park Avenue.
Prior to July 2010, the ten blocks between 46th Street and 56th Street were without the city's usual pedestrian crossing signals and overhead traffic lights because the railroad tunnel ceiling, which is also the street, is not thick enough for their poles' foundations. (These intersections did however have upright pole-mounted traffic lights prior to 2010.)