Entrance to the Tagus estuary, from Mar da Palha to Cascais

João Vicente Casale (1539-1593) and his nephew, Alexandre Massai, Italian engineer-architects, were brought to Portugal by King Filipe I to study the military reinforcement of Lisbon’s estuary. When he arrived in 1589, Massai was commissioned to build the Fort of São Lourenço da Cabeça Seca, now better known as the Forte do Bugio, which still marks the entrance to Lisbon by sea. In 1617, now with King Filipe II on the throne, Massai was given the task of drafting a report on the silting up of the Tagus estuary. 

Much of his work was constructed on the Algarve and the Alentejo coast, as is evident from his forts on the island of Pessegueiro, in Vila Nova de Milfontes and in Sines. He also surveyed the fortifications along the kingdom's southern coast, from Cacela to Sagres, and many others on the Alentejo coast. This project resulted in the manuscript Descripção do Reino do Algarve [Description of the Kingdom of the Algarve], a military codex produced at a time when defences along Portuguese coast were being reinforced to better respond to attacks by corsairs. The codex included this drawing, on folios 79 and 80.