Historians and geographers are always delighted by the promise of fire insurance maps and this collection will only add to the excitement. Made available by the University of Colorado Libraries, this set of Sanborn fire insurance maps consists of 346 maps that “show residential, commercial, and industrial uses of sites, building footprints, potential environmental hazards, and construction details of structures” from 1883 to 1922. First-time visitors will appreciate the broad scope of maps that cover everything from industrial sites in Denver to low-density towns in the northeastern corner of the state. More familiar visitors will love the Advanced Search feature that allows users to look for specific items and Community Tools provides wiki based resources on how to use these maps more efficiently.