Travel back in time with a visit to the historic center of Lima, which boasts stellar examples of Spanish colonial architecture. Start at the central Plaza de Armas (also called the Plaza Mayor), site of the 17th-century baroque cathedral and the adjacent Archbishop's Palace. On the north side of the square, on the banks of the Rimac River, sits the Government Palace, the residence of Peru's president. Tours of the palace can be arranged in advance—or just wait outside at noon to catch the changing of the guards. Later, stroll the streets around the plaza to admire the colonial-era mansions, then head slightly south to visit some of the museums in the Pueblo Libre area.