The university campus is actually one vast arboretum, with lots of peculiar, fragrant and beautiful plants. Here are some greatest hits: Download a podcast guide to the dreamy 110-year-old olive walk along the west edge of campus. Wait for March, and walk the arching green tunnel of sour-orange trees in swoony fragrant bloom, just east of Gila Hall. Or sit down in the shade of the sycamore just east of the Kuiper Sciences Building: This is one of the moon trees, grown from a seed that went to the moon with the Apollo 14 mission in 1971. The website tells you what's in bloom in each of Tucson's seasons, and shows five different plant walks you can follow like a treasure hunt.