Portico Row consists of sixteen houses on Spruce Street designed by Thomas Ustick Walter, who later went on to design the U.S. Capitol Dome. When constructed in 1831, it was the  most architecturally ambitious of several long rows of stately townhouses built on the edges of the rapidly expanding city. Over the years, as the city grew, Portico Row survived. The other rows did not. Portico Row was placed on the National Register of Historic Places in 1977 because of its significance “as an example of early 19th century upper-middle class housing… and the only remaining row of its original scale and appearance” in Philadelphia.