The lovely, shady Jardim Dr Santiago, at the eastern end of Praça Sacadura Cabral, is a delightful place. There are good views, a bandstand and shady, flowering trees. It’s a favourite spot for elderly men to sit and chat, particularly after a soak in the thermal bath at the entrance to the garden. There's also a small playground in the northwest corner.
You can join the locals for a soak in a basic bath (open weekdays), but don't expect any luxury (it's basically a bathtub in a dimly lit room). Bicarbonated calcium waters, said to be good for rheumatism, burble from the richly marbled Fonte das Três Bicas (Fountain with Three Spouts) by the entrance to the jardim.