The Centro Histórico (Historic Centre) is the heart of old Quito — the neighbourhood that earned the city its UNESCO World Heritage status in 1978, the first city in the world to receive that designation. It is an area of roughly two square kilometres that contains more than 40 churches, 17 plazas, and dozens of convents, monasteries, and colonial mansions, most of them dating from the 16th to the 18th century and most of them in remarkable condition.
Walking the Centro Histórico is the primary reason to visit Quito. The streets are steep, the colonial facades continuous, and the life of the neighbourhood — market stalls, school children, pilgrims, street vendors — goes on entirely around the tourists rather than for them. The main arteries are García Moreno and Venezuela streets running north-south, with the Plaza Grande (main square) as the centre of gravity. Allow at least a full day; two is better if you want to go inside the major churches and museums.