Pecos National Historical Park is the essential stop: a short trail passes the remains of Pecos Pueblo and the roofless Spanish mission church, with the Sangre de Cristo foothills rising behind them. The visitor centre gives useful context before you walk, especially on how this became a meeting point for Pueblo, Plains, Spanish and American worlds.
The park also protects stretches of the Santa Fe Trail and parts of Forked Lightning Ranch. Give it at least two hours, more if you want to take the ranger guidance for Glorieta Pass.