The post office, a large, triple-cross-vaulted structure in reinforced concrete, is enclosed by a purely functional wall which diminishes any sense of its true scale and makes it look unimpressive. While under construction as three vast, billowing enclosures of space coming to the ground without any interior supports, however, it was impressive indeed. It was built at a time when such vaulting in reinforced concrete, developed by European engineers such as Pier Luigi Nervi in Italy, was just being discovered in the United States and similarly employed in the near-contemporaneous three-vaulted concourse for the St. Louis Airport (1951–1958, Hellmuth, Obata and Kassabaum). This was the first fully automated post office in the United States, employing then radical German technology, since modified, as an experiment toward speeding the mail. It was also in the vanguard of the warehouse type of postal operation in an industrial park outside the city center, which funnels all mail coming to or originating in a region through a large-scale facility. As such, it marks the beginning of the end of the downtown city post office for pride of place in the postal system.