The Irwin Union Bank building was built in 1954. It was designated as a National Historic Landmark by the National Park Service in 2001 in recognition of its unique architecture. The building consists of a one-story bank structure adjacent to a three-story office annex. A portion of the office annex was built along with the banking hall in 1954. The remaining larger portion, designed by Kevin Roche John Dinkeloo and Associates, was built in 1973. Eero Saarinen designed the bank building with its glazed hall to be set off against the blank background of its three-story brick annex. Two steel and glass vestibule connectors lead from the north side of this structure to the annex. The building was designed to distance the Irwin Union Bank from traditional banking architecture, which mostly echoed imposing, neoclassical style buildings of brick or stone. Tellers were behind iron bars and removed from their customers. Saarinen worked to develop a building that would welcome customers rather than intimidate them.