Red Rock Canyon is a 1474 acre recreation area just outside of Old Colorado City, only 4 miles west of downtown. While there are more than 10 miles of trails through rust colored ridges of sedimentary rock, the most popular for running is the 5 mile moderately trafficked loop combining the Hogback and Mesa trails. This route is smooth enough for all skill levels. Note it is hilly, with two good foot climbs, averaging 6-7% grades. PRO TIP: Lovely wildflowers in season.
The linked to map has additional information on the park and other trails.