The Four Seasons Private Residences Denver, the 45-story luxury condo building and hotel that's been under construction since September 2007, is set to be topped off this Thursday at 10:30 a.m. with the ceremonial hoisting into place of the 75-foot mast that will crown the structure. With the spire, the building will reach 641 feet. That's quite a change from some of the first buildings to grace the spot, like Governor John Evans' squat brick house that stood at the corner of 14th and Ara