Located next to the sea, it is believed that the first fortification sited on the bar of the River Lima estuary dates from the reign of King Afonso III (13th century). However, the earliest certain date is the 15th century, when a fortress was built there that would have been completed in the following century, in the reign of King Manuel I. This is indicated by various Manueline architectural features, notably the 'Roqueta Tower' in the south-west bastion of the present fortress.
In the late 16th century, the fortress underwent a series of improvement works, having already been under Spanish domination in the reign of Philip II (Philip I of Portugal). And so the current fortress, with its polygonal floor plan, was built based on a design by Filippo de Terzi, the most famous architect of military buildings of that period.
References:The Villa d'Este is a 16th-century villa in Tivoli, near Rome, famous for its terraced hillside Italian Renaissance garden and especially for its profusion of fountains: the extraordinary system contains fifty-one fountains and nymphaeums, 398 spouts, 364 water jets, 64 waterfalls, and 220 basins, fed by 875 meters of canals, channels and cascades, and all working entirely by the force of gravity, without pumps. It is now an Italian state museum, and is listed as a UNESCO world heritage site.
Tivoli had been a popular summer residence since ancient Roman times due to its altitude, cooler temperatures and its proximity to the Villa Hadriana, the summer residence of the Emperor Hadrian I.
The Villa was commissioned by Cardinal Ippolito II d'Este (1509-1572), second son of Alfonso I d'Este, the Duke of Ferrara and grandson of Pope Alexander VI, along with Lucrezia Borgia.