CASA GRANDE RUINS NATIONAL MONUMENT

CASA GRANDE REMAINS one of archaeology’s biggest cold cases, despite being the nation’s oldest archaeological preserve. That’s what Diane Garcia, an interpretive ranger, likes about it. “There’s a lot of mystery still,” she says. “People are always coming up with new ideas.” Thought at different times to be a fort, a granary, a temple or a watchtower for the complex canal system that surrounds it, the four-story house stands apart in the context of a large city and surrounding villages. “What we had here is more like Tucson,” Garcia says. “It was a city. For all we know, the ‘great house’ was a hotel for people who were passing through.” Formerly one in a series of “great houses,” only Casa Grande remains. When you listen, Garcia says, you can hear the owls and bats that nest inside it. “You start thinking you can hear other things — that you can hear the past.”