Banks are plentiful and most have 24-hour ATMs, which tend to offer the best exchange rates. For extra security use ATMs inside banks (as opposed to ones on the street or in supermarkets), cover the key pad as you enter passwords and graze the whole keypad to prevent infrared tracing of passwords. Avoid making withdrawals late at night.
Lima’s casas de cambio (foreign-exchange bureaus) give similar or slightly better rates than banks for cash, although not traveler’s checks. They’re found downtown on Ocoña and Camaná, as well as along Av José Larco in Miraflores. Consider using street moneychangers carefully as counterfeit is a problem.
Banco de Crédito del Perú Has 24-hour Visa and Plus ATMs; also gives cash advances on Visa, and changes Amex, Citicorp and Visa traveler’s checks. The Central Lima branch has incredible stained-glass ceilings. There's another branch at José Pardo.
BBVA Continental A representative of Visa; its ATMs also take Cirrus, Plus and MasterCard.
LAC Dólar A reliable exchange house; can deliver cash to your hotel in exchange for traveler’s checks.
Travex Buy traveler’s checks or replace lost ones.