The Allegheny County Courthouse and Jail is Henry Robson Richardon's masterpiece. Richardson, one of America's most important architects of the 19th century is known for his romanesque building style, known as Richardsonian Romanesque.
During his short career, H.R. Richardson built many outstanding buildings, including the Marshall Field Store in
Chicago and
Trinity Church in
Boston.
The Allegheny Courthouse & Jail consists of two separate buildings, connected via the bridge of sighs, a romanesque version of the famous namesake in Venice. The complex has typical Richardsonian Romanesque features, including romanesque arches, turrets, gothic dormer windows and massive walls of Worcester granite blocks. The largest blocks, weighing more than 5 tons were used for the jail, a large turreted block of seemingly impenetrable granite.
The courthouse

across Ross Street consists of a large rectangular block built around a spacious landscaped courtyard, allowing sufficient ambient light to enter the building. The block includes the courthouse tower, rising more than 250ft (76m) high.
The lobby of the courthouse is a large vaulted space with large stairs of polished granite and decorated with magnificent murals by Vincent Nesbert. Unfortunately after the entrance was moved one level lower, visitors do not enter the building via the impressive lobby anymore.
The jail (now a courthouse facility) was completed in 1886. That same year Richardson died at age 47 after a career of only 20 years. The courthouse was completed two years later, in 1888.
The architectural importance of the Allegheny Courthouse & Jail was recognized in 1974 when the building was listed in the National Register of Historic Places.