What's the oldest building in Pueblo?

Most of the oldest Pueblo buildings are downtown near Union, Abriendo and Main. The buildings down there tend to have the date of construction on them some where, and it's a lot of fun to walk down the street reading up on the history of each one. Here's a website for more information if you ever feel like taking a historical tour. http://www.historicpueblo.org/documents/historiclandmarks.pdf