Main Street/Market Square Historic District, Historic commercial district in downtown Houston, Texas, United States.

Main Street/Market Square Historic District is a commercial preservation area in downtown Houston containing 52 historic structures, a viaduct, and two public parks along the bayou. The buildings span multiple blocks and represent architectural styles from the late 1800s through early 1900s.

The collection began in 1836 when Augustus and John Allen established the area as Houston's original commercial center while Texas was still an independent nation. Most surviving structures were built between the mid-1800s and 1930s during the city's period of rapid economic expansion.

Market Square Park takes its name from the four city halls and city markets that once stood on the site. Nearby, the Kennedy Bakery Building at 813 Congress recalls Irish-born baker John Kennedy, who also owned the property at 214 Travis and began a building there in 1860. The Magnolia Brewery Building at 110 Milam and the adjacent Magnolia Ballroom at 715 Franklin were built by the Houston Ice and Brewing Company.

Market Square Park within the district provides open space with water features, seating, and direct connections to multiple preserved structures from the 1800s. Walking through the district is straightforward, with clear paths and adequate signage to guide visitors through the blocks.

The site hosted four successive Houston City Halls that were each destroyed by fire before the current park layout was created. This pattern of repeated destruction shaped the area's development in a way few other places have experienced.