Reached through an underground entrance across the garden from the Coricancha [1], the rather unimpressive Museo de Sitio Coricancha (Av. El Sol, 9 a.m.–6 p.m. Mon.–Sat., 8 a.m.–1 p.m. Sun., entry with boleto turístico), which exhibits a few artifacts from the excavation of Coricancha, a model of the sun temple, and blueprints of its floor plans. There are no guides available here, and explanations are in Spanish only.
On your way back to the Plaza de Armas [2], walk down the narrow alley of Loreto. To your right are the Inca walls of the acllahuasi, now the Santa Catalina convent. To the left are the walls of the palace of Huayna Cápac, now the Iglesia de la Compañía [3].
Links:
[1] http://www.moon.com/destinations/peru/cusco/sights/east-the-plaza-de-armas/coricancha-and-santo-domingo
[2] http://www.moon.com/destinations/peru/cusco/sights/plaza-de-armas
[3] http://www.moon.com/destinations/peru/cusco/sights/plaza-de-armas/iglesia-de-la-compania