@MDT these are skylights for basements. Also they were needed for the Seattle Underground Seattle Underground - Wikipedia https://en.wikipedia.org/wiki/Seattle_UndergroundThe glass was clear but due to a reaction with the sun they changed purple. More hereBackstory: How Pioneer Square's Purple Sidewalk Skylights Came to Be - Seattle magazine https://seattlemag.com/food-and-culture/backstory-how-pioneer-squares-purple-sidewalk-skylights-came-be/
