Two images dominate the north side of the Square: The Washington Arch, and the houses of Washington Square North also called, "The Row." The stately arch, commissioned to celebrate the centennial of Washington's inauguration, serves as the entry into the park from the north.

Designed by architect Stanford White, it is intended to reflect a classic Roman style and is constructed from white marble. The Row was built on land leased from Sailors' Snug Harbor, a home for retired seamen. Since the construction of the first residence, a federal-style mansion built in 1828-1829 for George P. Rogers at No. 20 Washington Square North, this fashionable block has been the home of statesmen, artists, merchants, and lawyers. In the 1830s, architects designed the group of houses on this block, especially "The Row," 1-13 Washington Square North, in the Greek Revival style, which is characterized by doorways framed by Doric or Ionic columns, classical motifs on the lintels and moldings, and plain brick fronts. The south side of the Square began the century boasting fine federal style houses, and Judson Memorial Church. The houses soon fell into decay. They began a long run as boarding houses, cafes and small shops, generally serving as an inexpensive alternative to the more elegant environs north of the Square. The south side also felt the pressure for housing from further south and southeast. The vast immigrant populations that were dominating those areas of the city fueled a demand for cheap housing. In fact, tenements became the most popular form of housing along Bleecker Street and further south beginning in the 1850's.

While the other three sides of the Square grew rapidly, it was not until after the 1840's that the west side of the Square began developing. Restaurants and beer gardens cropped up and the elegant Hicks-Lord house, the Progressive Party Clubhouse and the Trinity Trade School were also built. Further to the west of the Square, Sixth Avenue was a bustling commercial thoroughfare, with shops in sturdy brick buildings lining the avenue.

Washington Square East was dominated for most of the 19th century by the white marble NYU University building and the South Dutch Reformed Church, both neo-Gothic in style. Along with the north side of the park, the east side was considered a highly desirable locale. Lafayette Place featured Colonnade Row, nine marble fronted houses all connected by a continuous Corinthian colonnade. A little further to the west, a mansion owned by Samuel Ward (the first treasurer of NYU) graced Broadway and Bond, helping to make Bond one of the most prestigious streets in the city during the mid-1800's. By the end of the century, Broadway was beginning to be devoted to commercial interests, and the quality of the housing in the area deteriorated.