Originally all wood, the young city was destroyed in the Great Seattle Fire of 1889. The whole area was rebuilt with stone and brick in the Renaissance Revival style; this distinct character remains. After the fire the street level was raised one story to prevent flooding (most of Pioneer Square was once an island). There now exists an entire level of storefronts below ground, accessible only through the underground tour which walks groups along the historic streets and storefronts buried below Pioneer Square.
Pioneer Square is the origin of the term “Skid Road”. And if you visit the area now, several entities are immediately obvious; many very high-class art galleries, upscale restaurants & bars, and a distinctive transient population. It is a unique contrast and speaks to Seattle as a whole.
Every first thursday of the month the Pioneer Square Art Walk is held. You can see a hand blown glass demonstration and peruse many contemporary art galleries.