Market Street is the core of Warren, or, in deference to its four religious structures, the soul of Warren. Rarely does one find such a wealth of architecture in popular nineteenth-and twentieth-century styles in a city, let alone on one street. The only style missing is Georgian Revival, but a stone example is located around the corner at 215 4th Avenue. Within six blocks are buildings dating from the Greek Revival house of 1830 at 117 Market Street to the County Jail of 1975 at number 407 behind the courthouse. Several churches include the stone Romanesque Revival First Presbyterian Church by Cleveland architect Sidney R. Badgley (1894; 300 Market Street); the stone First United Methodist Church by Philadelphia architects Charles Weber Bolton and Son (1925; 200 Market Street); and the brick, Classical Revival First Baptist Church (c. 1925; 208 Market Street). Charles D. Wetmore of the New York City firm Warren and Wetmore designed the Warren Public Library (1915–1916; 205 Market Street) with inscriptions written by Charles W. Eliot, former president of Harvard, Wetmore's alma mater, carved into the limestone frieze above fluted Ionic columns.
Some of the houses have been adapted for new uses. The Conewango Club (1905; 201 Market Street), a five-bay, red brick Colonial Revival building with a two-story Ionic-columned portico by Edward A. Phillips was partially destroyed by a fire in June 2002, but has been restored by Linn Hyde. Washington, D.C., architect Carl Keferstein designed the crenellated brick castle (1886; 603 Market Street) for his sister. A handsome trio of Italianate houses c. 1868 has been reused as offices; a Church of Christ, Scientist, reading room; and a clubhouse. The frame Italianate house at number 301 is a stellar example of the style and represents the predominance of frame buildings in Warren. A modern house of 1955 at 511 Market Street is now an art gallery. The reuse of these residential buildings maintains the nineteenth-century ambience of the town.