Ruby is one of southern Arizona's better-preserved ghost towns, set in lonely country west of Nogales. The old mining settlement still has standing buildings, mine relics, and a resident caretaker, which gives it more substance than many desert ruins.
The road includes an unpaved stretch, so treat it as a half-day excursion rather than a downtown sight. It is the strongest reason to base a borderlands day around Nogales instead of only passing through.