This reservoir is hidden under the Jardim do Príncipe Real, more precisely beneath the lake. Its building work was completed in 1864, and it has a total capacity of roughly 880 m3. 

It was one of the first reservoirs of the modern water distribution network, designed in 1856 by the French engineer Louis-Charles Mary.

The Patriarchal Reservoir was originally supplied by the Águas Livres Aqueduct, and then, after 1890, by the Alviela Aqueduct. It is octagonal in shape, with 31 pillars supporting the stone arches of the vaulted ceilings.

Ticket: 2€ (single price for all ages from 7 years old (inclusive))
Meeting point: Reservatório do Príncipe Real, Jardim do Príncipe Real, Lisboa
Accessibility: not recommended for people with reduced mobility. Presence of stairs.
Open: 13/06/2024 to 27/10/2024, Thursday to Sunday, 12am – 7pm 
Last admission: 30 minutes before closing.