8 / 16 K.J. Winkleman, courtesy Idaho Botanical Garden

Usually, the only things that flourish on old prison grounds are ghosts and myths. But the Idaho Botanical Garden has brought new life to what was the state penitentiary for more than a century. Head to the Meditation Garden, which is filled with trees planted by inmates in the 1960s and which can be 20 degrees cooler than other parts of the garden in midsummer.

$7; 2355 Old Penitentiary Road, Boise; idahobotanicalgarden.org.