Pioneer Square is a neighborhood in the southwest corner of Downtown Seattle, Washington, USA. It was once the heart of the city: Seattle's founders settled there in 1852, following a brief six-month settlement at Alki Point on the far side of Elliott Bay. The early structures in the neighborhood were mostly wooden, and nearly all burned in the Great Seattle Fire of 1889. By the end of 1890, dozens of brick and stone buildings had been erected in their stead; to this day, the architectural character of the neighborhood derives from these late 19th century buildings, mostly examples of Richardsonian Romanesque.
The neighborhood takes its name from a small triangular plaza near the corner of First Avenue and Yesler Way, originally known as Pioneer Place. The Pioneer Square-Skid Road Historic District, a historic district including that plaza and several surrounding blocks, is listed on the National Register of Historic Places.
Like virtually all Seattle neighborhoods, the Pioneer Square neighborhood lacks definitive borders. It is bounded roughly by Alaskan Way S. on the west, beyond which are the docks of Elliott Bay; by S. King Street on the south, beyond which is SoDo; by 5th Avenue S. on the east, beyond which is the International District; and it extends between one and two blocks north of Yesler Way, beyond which is the rest of Downtown. Because Yesler Way marks the boundary between two different plats, the street grid north of Yesler does not line up with the neighborhood's other streets so the northern "border" of the district zigzags along numerous streets.
In some places, the Pioneer Square-Skid Road Historic District extends beyond these borders. It includes Union Station east of 4th Avenue S., and several city blocks south of S. King Street.