The Padmanabhaswamy Temple is the city's defining monument — a seven-storey Dravidian gopuram (gateway tower) that rises above the old fort district and draws pilgrims from across the subcontinent. The presiding deity is Vishnu in his cosmic sleep form, reclining on the great serpent Ananta across a length of several metres, a posture requiring three separate shrines to encompass. The image is accessible only through three doors, and only at specific times of day.
Non-Hindus are not permitted inside the temple, which is a genuine restriction — this is an active and deeply important place of worship, not a heritage site managed for tourism. But the towering gopuram and the atmospheric streets of the fort district around it are worth visiting regardless. The morning puja, with its drums and bells audible from outside the walls, gives you some sense of what happens within.