It was thru the Jesuit priest Antonio SedeÃ±o that the use of stone in building was introduced in Manila. After the great fire of 1583 where candles for the funeral of the fourth Governor General, Gonzalo Ronquillo de PeÃ±alosa, consumed the then simple San Agustin Church and engulfed much of the other structures within the city, SedeÃ±o proposed to then Bishop Domingo de Salazar to rebuild the episcopal house with the material, adobe from Guadalupe. After this, he built another structure of stone for the Jesuits.
Governor General Santiago de Vera then asked that SedeÃ±o fortify the southern flank of Manila, the one facing Bagumbayan (now the Luneta) and just beside the beach (later to be reclaimed by the Americans to build present day Roxas Boulevard). There, he built a towering fortification, the Fuerza de Nuestra SeÃ±ora de Guia, in 1586-1587 that was medieval in design. Rene Javellana, SJ, writing in Fortress of Empire mentioned that the design was derided for its design, being obsolete, and a waste of money.
Damaged by an earthquake, the seventh Governor General, Gomez Perez Dasmarinas in 1593, had the top courses of stone removed and the rest integrated to the walls, the cortina or curtain that he started building in 1590. Between 1653 and 1663, it was integrated into a new baluarte, resembling an ace of spades. The British invasion of 1762 breached the walls and the earthquake of 1863 damaged this part and later destroyed during the Battle of Manila in 1945. It was in 1979 to 1992, part of the restoration of Intramuros that the Baluarte de San Diego took its present shape.
In 1984, archaeological diggings on the Bastion de San Diego led to the discovery of the concentric circles that can be seen today. It was proposed that the this was SedeÃ±o’s tower which was later converted into a cistern, thus these circles. Today, gardens and pergolas have been added and the area not only for visitors but can be used for special events.