Due to its long coastline, Portugal has developed several defensive systems throughout history. From medieval fortifications to modern artillery batteries and bunkers, these structures were strategically placed along the coast and played a crucial role in the development of both the territory and urban areas. This research focuses on a specific site that was vital for the defense of Lisbon and Setúbal: Outão.

Due to its strategic location at the entrance of the Sado River, this place has witnessed military occupations across different historical periods. The first military occupation was a 12th-century fortification, followed by a complementary 17th-century fortification, and later, a modern artillery battery constructed after World War II.

Today, the battery is deactivated, and the site has been left abandoned. This presents an opportunity to reflect on the future of this heritage site.