There are thousands of varieties of citrus, many more than just the navel oranges. And they’re all being preserved in a collection at the University of California Riverside.

Ostracism at the Athenian Agora

An audio guide to the world’s strange, incredible, and wondrous places. Co-founder Dylan Thuras and a neighborhood of Atlas Obscura reporters explore a new wonder every day, Monday through Thursday. In under 15 minutes, they’ll take you to an incredible place, and along the way, you’ll meet some fascinating people and hear their stories. Our theme and end credit music is composed by Sam Tyndall.