Union Square is a skyscraper complex at Sixth Avenue between Union and University Streets in Downtown Seattle, Washington, adjacent to Freeway Park. It consists of two skyscrapers built in the 1980s and primarily used for office space. The entire complex features a 1,100-stall parking garage, a courtyard, a retail plaza spanning three stories and an underground pedestrian concourse that connects with the Fifth Avenue Theater and Rainier Square. Both structures were awarded LEED certification in 2009 and eventually received LEED Platinum certification 6 years later as a result of reduced annual energy consumption by 40 percent through recent renovations. The entire complex is currently managed by Washington Holdings, a real estate firm also known as Union Square LLC which is based in Seattle.

Downtown is the central business district of Seattle, Washington. It is fairly compact compared with other city centers on the U.S. West Coast due to its geographical situation, being hemmed in on the north and east by hills, on the west by Elliott Bay, and on the south by reclaimed land that was once tidal flats. It is bounded on the north by Denny Way, beyond which are Lower Queen Anne, Seattle Center, and South Lake Union; on the east by Interstate 5, beyond which is Capitol Hill to the northeast and Central District to the east; on the south by S Dearborn Street, beyond which is Sodo; and on the west by Elliott Bay, a part of Puget Sound.