When it came time to build Seattle’s original city, Pioneer Square was carved out of lush forestland alongside Elliott Bay. Despite this location, businesses in the area suffered from flooding and sewage backup due to tides.
The City decided to raise the street level in order to fix this problem. It took a while, but eventually, the city completed its plan, and by 1889, Pioneer Square was elevated a full floor above street level.
Alongside this elevation, the city also installed glass prisms that let light into basements and storage spaces beneath the sidewalks. The prisms were created by changing the shape of a glass block to a prismatic design, allowing it to reflect light more effectively.
These glass blocks were first introduced to the world at Chicago’s 1893 Columbian Exposition. Originally designed to increase light through window openings, they were later adapted for floors and sidewalks.
Today, these glass prisms can be seen throughout Washington in cities from Port Townsend to Tacoma. They are a unique feature of the urban landscape, but they are often heavily damaged or poorly maintained.
Thankfully, the National Trust is working with the Alliance for Pioneer Square to help restore these unique features in the neighborhood’s historic district. This effort is part of The Cities Project by Heineken, a crowd-funding campaign to restore ten public spaces in cities around the country.
In May 2017, the National Trust and the Alliance launched the campaign with a goal of raising $40,000 to support restoration efforts for the prisms. That work continues on today as more owners look to recapture the historic beauty of the past.
One of the biggest challenges was empowering the property owners in the district to effectively steward, repair, and maintain the character-defining prisms. Creating a resource guide to assist property owners in efficiently repairing and preserving the historic glass sidewalks has been a major focus of this project. Please see the link below.
The manual covers everything from the history of the prisms to their materials, installation, and refracting systems to the tools and techniques to use when repairing them. In addition, it will offer technical assistance to help property owners identify and prioritize areas of concern. PIONEER SQUARE GLASS PRISM MANUAL