The Jesuit Iglesia de San Pedro, two blocks from Plaza Mayor, has the best-preserved colonial church interior in Lima — much of the 17th-century gilded carved-cedar altarpieces, painted ceiling, and tiled chapel walls survived because the church was not refurbished in the 19th or 20th centuries.
Inside is a vast retable of carved wood covered in gold leaf, a separate side chapel of Saint Ignatius with painted azulejo lining, and a small museum of religious art in the adjoining sacristy. Easily combined with a visit to the Plaza Mayor next door.