A city unto itself, this 5-acre complex of mud-brick, Iberian-style buildings—a working convent and one of Peru's most famed cultural treasures—is surrounded by vibrant fortress-like walls and separated by neat, open plazas and colorful gardens. Founded in 1579 and closed to the public for the first 400 years, Santa Catalina was an exclusive retreat for the daughters of Arequipa's wealthiest colonial patrons. Now visitors can catch a peek at life in this historic monastery. Narrow streets run past the Courtyard of Silence, where teenage nuns lived during their first year, and the Cloister of Oranges, where nuns decorated their rooms with lace sheets, silk curtains, and antique furnishings. Though it once housed about 400 nuns, fewer than 30 call it home today. Admission includes a one-hour guided tour (tip S/15–S/20) in English. Afterward, head to the cafeteria for the nuns' famous torta de naranja (orange cake), pastries, and tea. There are night tours on Tuesday and Thursday, but check the times before you go, as they sometimes change.