On a budget, Jardim da Estrela & Basílica still earns its price.
Free
A leafy local breather — duck ponds, a bandstand café, big shade trees, with the grand domed basilica (free, climbable) across the road. The catch: there's no 'wow' sight, it's a tram ride from the centre, and it's really a place to slow down rather than tick off. Lovely antidote to viewpoint-and-queue fatigue.