First time offered for sale since original construction in 1979, listed at $537,000 Open House Sunday, August 4th, 1-5pm Fuller Sotheby’s International Realty (FSIR) invites you to enjoy the “Upside Down Tree House” designed by one of Colorado’s most accomplished architects, Karl Berg – Sunday, August 4th, from 1:00 – 5:00 p.m. at 7111 E. … More Open House | Architect Karl Berg’s Upside Down Tree House On The Market