São Luís  is a sprawling city spread out along an island peninsula. However, the oldest and most interesting parts are concentrated on the island’s tip, at the point where the Rio Anil flows into the Baía de São Marcos. Within the old city center, known as Centro , lies the neighborhood of Praia Grande. This colonial ensemble of cobblestoned streets and restored (and still crumbling) palaces falls under the jurisdiction of the Projeto Reviver  (which is why you’ll often hear the bairro referred to as “Reviver”).
Almost all of São Luís’s sights, and most of its action, are concentrated in this dense, fascinating, and easy-to-wander-around area. The only confusing aspect is that many streets have more than one name.