The Arca D’Água Garden, in Praça 9 de Abril, was inaugurated in 1928. Its underground structure dates back to the early 17th century, when the reservoirs served as a central point for supplying water to the city.
The redevelopment of the square in 2023 included the renovation of the pedestrian network, replacing the existing pavement with a more permeable one, promoting better articulation between the trees, paths and street furniture. These interventions increased the permeability of the square, preserved and improved the existing trees and infrastructure networks, and preserved the identity of the space in terms of the overall layout of the garden.
The naturalised management of this space allows the entire green area, the soil and the lake to contribute to thermal regulation, carbon sequestration and the consequent improvement of air quality, the conservation of terrestrial and aquatic biodiversity, and the natural infiltration of rainwater, preventing flooding in cases of heavy rainfall.
Its 22.000 m² are home to more than 200 specimens of various relevant tree species, notably 96 plane trees (Platanus acerifolia), 57 japanese camellias (Camellias japonicas) and, of course, 13 southern magnolias (Magnolia grandiflora), classified in 2021 by the Instituto de Conservação da Natureza e Floresta (ICNF) as a set of public interest.
