The walk heads directly northeast to Museo del Área Fundacional, which opens at 9:00 am. This is where the colonial city actually stood — the museum is built directly over the excavated remains of the colonial Cabildo, whose final building dated to 1749 before the earthquake brought it down. Archaeologists uncovering the site in the late 1980s found more than 80,000 fragments of ceramic, bone, and Huarpe tools, along with the original tile floors of the capitular rooms. The museum presents these layers in sequence — pre-Columbian, colonial, post-earthquake — and the Ruinas de San Francisco stand immediately alongside: the remains of a Jesuit complex begun in 1645, later passed to the Franciscans, whose 15-metre columns, nearly two-metre-thick walls, and two surviving arches give some sense of the scale of what the earthquake took down in 1861.