Thanks for the feedback. Yes, its a really thick wall that reaches through many levels, but not all levels. Here is the odd-looking staircase surrounded by those thick walls:
https://www.flickr.com/photos/marantzer/4345032638/
Speaking of the 3D work, here are more examples in the same city
Union Station: https://demo.f4map.com/#lat=39.7533276&lon=-105.0004084&zoom=20&camera.theta=67.345&camera.phi=20.283
Denver Art Museum https://demo.f4map.com/#lat=39.7375104&lon=-104.9881734&zoom=20&camera.theta=67.681&camera.phi=-21.966
Denver Greek Theater: http://demo.f4map.com/#lat=39.7381045&lon=-104.9888202&zoom=21&camera.theta=72.502&camera.phi=-152.543
Fisher Tower with two skybridges in the background: http://demo.f4map.com/#lat=39.7488729&lon=-104.9959798&zoom=20&camera.theta=46.089&camera.phi=15.126
Auraria rooftop details: http://demo.f4map.com/#lat=39.7446459&lon=-105.0016751&zoom=20&camera.theta=68.033&camera.phi=15.126
Three rooftop water tanks: http://demo.f4map.com/#lat=39.7501368&lon=-105.0030764&zoom=20&camera.theta=74.45
Coors Field: http://demo.f4map.com/#lat=39.7560417&lon=-104.9942011&zoom=19&camera.theta=73.468&camera.phi=-165.137
Downtown church: http://demo.f4map.com/#lat=39.7402251&lon=-104.9829452&zoom=20&camera.theta=73.468&camera.phi=101.976
Auraria church - note the two crosses placed on the roof just for some nice (and accurate) detail: http://demo.f4map.com/#lat=39.7427533&lon=-105.0022680&zoom=21&camera.theta=50.55&camera.phi=99.627
Pavilions roof details along with a road through the building: http://demo.f4map.com/#lat=39.7435407&lon=-104.9905719&zoom=20&camera.theta=68.999&camera.phi=-90.882
