Mashable has published a photo essay which looks back at the original Penn Station.
In 1910, when New York City transportation terminal Pennsylvania Station opened, it was widely praised for its majestic architecture. Designed in the Beaux-Arts style, it featured pink granite construction and a stately colonnade on the exterior.The main waiting room, inspired by the Roman Baths of Caracalla, was the largest indoor space in the city — a block and a half long with vaulted glass windows soaring 150 feet over a sun-drenched chamber. Beyond that, trains emerged from bedrock to deposit passengers on a concourse lit by an arching glass and steel greenhouse roof. This may sound unfamiliar for present-day residents of New York City, who know Penn Station as a miserable subterranean labyrinth. Though the original Penn Station served 100 million passengers a year at its peak in 1945, by the late 1950s the advent of affordable air travel and the Interstate Highway System had cut into train use. The Pennsylvania Railroad could not even afford to keep the station clean.
The station was demolished in the early 1960s for the construction of the fourth iteration of Madison Square Garden, which was originally located across town, hello, at Madison Square. Hit the link and lament.