This photo comes from the Denver Public Library Western History Collection. They estimate that it was taken between 1905 and 1908.

Several of the buildings are still with us, as shown in Pat Klein's drone photo.

Wrong Side of the Street!
I misinterpreted the old Transcript articles when researching yesterday's article about 1600 Jackson. The post office that collapsed in 1969 was south of 17th, not north of 17th. That's now the site of the Mines dormitory.
Thanks to Rick Gardner for clarifying this point!