The Washington Avenue Historic District is located in Downtown West, St. Louis, Missouri along Washington Avenue, and bounded by Delmar Boulevard to the north, Locust Street to the south, 8th Street on the east, and 18th Street on the west. The buildings date from the late 19th century to the early 1920s. They exhibit a variety of popular architectural styles of those years, but most are revival styles or in the commercial style that would later come to be known as the Chicago School of architecture. Most are large multi-story buildings of brick and stone construction, built as warehouses for the St. Louis garment district. Many have terra cotta accents on their facades. After World War II, the decline in domestic garment production and the preference for single-story industrial space led to many of the buildings being vacant or underused due to functional obsolescence.

St. Louis is an independent city in the U.S. state of Missouri. It is located near the confluence of the Mississippi and the Missouri rivers. In 2020, the city proper had a population of 301,578, while its bi-state metropolitan area, which extends into Illinois, had an estimated population of over 2.8 million. It is the largest metropolitan area in Missouri and the second largest in Illinois. The city's combined statistical area (CSA) is the 20th largest in the United States.