The Museu da Água, or the Water Museum, is a unique museum dedicated to the history and importance of water supply in Lisbon. Housed in the beautiful Mãe d'Água Reservoir, the museum showcases the engineering marvels behind Lisbon's water distribution system. Visitors can learn about the city's water sources, reservoirs, and aqueducts through interactive exhibits and historical artifacts. With free admission on Sundays and public holidays until 2 pm, it is an educational and engaging museum for all ages.