Twentieth Street Viaduct, Spans Platte River Valley between Thirty-third Avenue & Blake Street, Denver, Denver County, CO

See also Union Pacific Railroad Warehouse, HABS No. CO-128
Significance: It is the longest of Denver's viaducts. Its length grew from the need to cross not only the Platte River but also Denver's extensive railyards, thus to alleviate the problem of train-automobile and train-pedestrian accidents. Its 85 spans of carying lengths are supported by steel columns and concrete piers. Long spans, bridging the river and the tracks, are carried by Warren trusses; short spans are carried by plate girders at either side of the roadway.
Survey number: HAER CO-51
Building/structure dates: 1911 Initial Construction