What lies beneath the office buildings and parking lots of Downtown Tucson is much of this town's history — and many of those who made it. • For decades, graves and bodies have been turning up during Downtown construction. • None compares, however, to the recent excavation of Tucson's National Cemetery, which took in the town's dead during the mid-1800s. • Learn about the painstaking process that went into excavating this particular burial ground — and why it's being called one of the country's largest historic cemetery exhumations ever. — Bonnie Henry