The architectural highlight of the historic center Arequipa  is the 425-year-old Monasterio de Santa Catalina (Santa Catalina 301, tel. 054/60-8282, www.santacatalina.org.pe , 9 a.m.–5 p.m. daily, 8 a.m.–8 p.m. Tues.–Thurs., US$11, guides work for a tip).
The monastery is a citadel built in 1579 entirely of sillar with a hundred houses, 60 streets, three cloisters, main square, church, cemetery, and painting gallery. As many as 175 nuns lived here during the 17th and 18th centuries, including the daughters of wealthy families, who lived in private houses with up to four servants. More than 400 colonial paintings, mostly from the Cusco School, hang in a gallery that was once a shelter for widows, single mothers, and homeless women.
One of the most prominent nuns was Sor Ana de los Ángeles Monteagudo (1620–1686), who was elected Mother Prioress of the monastery. A series of miracles were attributed to this nun, even after her death, which made the nuns of the monastery write a petition to the Vatican to try to make her saint. The process continues.
Today, there are a few nuns living in modern quarters in the convent; they subsist on tourist entry fees. The nuns were shut off from the rest of the city until 1985, when they became half-cloistered, meaning they can now leave and shop for food or visit relatives (up until that year, they spoke with families only through screened windows).
Photographers should visit late in the afternoon, when the light falls across the buildings at interesting angles.