Mirador de San Cristobal

You can see the whole city of Cusco from here, including the red tile roofs and the Plaza de Armas. The viewpoint is right outside a 16th-century church. This church was actually built on top of old Inca walls, which is a cool bit of history.

The walk up from the main square is short but very steep. Since you are at 3,400 meters, you will likely feel out of breath. Take your time and bring some water. It is a solid spot to get your bearings and see the surrounding mountains.