The great domed cathedral that dominates the old city's skyline was begun in 1722 and not completed until 1838 — the delays explain the mixture of Baroque and Neoclassical styles visible in different parts of the building. The interior is large and ornate without being oppressive: the choir stalls are worth examining closely, and the crypt below contains the tomb of the composer Manuel de Falla.
Climb the Torre de Poniente (west tower) for what are arguably the best views in the city — the full sweep of the old peninsula, the bay, and the Atlantic beyond. Entrance to the tower is separate from the cathedral and can be booked at the ticket office beside the main door. The climb involves narrow spiral stairs and is not suitable for anyone with severe vertigo.