From Plaza Regocijo [1], walk down Garcilaso to Iglesia San Francisco (8 a.m.–noon and 3–5 p.m. daily), a convent and church that stands above the plaza of the same name. This church, with three naves and in the shape of a Latin cross, was built in 1572 and is one of the few churches in Cusco [2] to survive the 1650 earthquake. As a result, its convent is one of the few remaining examples of the highly ornate 16th-century plateresque style, complemented here by azulejo tiles imported from Seville.
There are two smaller colonial churches down Santa Clara from here toward the market and the train station: The first is Iglesia Santa Clara (8 a.m.–noon and 3–5 p.m. daily), which is open only for early-morning mass 6–7 a.m., and the second is Iglesia San Pedro (8 a.m.–noon and 3–5 p.m. daily).
Links:
[1] http://www.moon.com/destinations/peru/cusco/sights/southwest-the-plaza-de-armas/plaza-regocijo
[2] http://www.moon.com/destinations/peru/cusco