The Outao Coastal Battery is an abandoned military site above the entrance to Setubal harbour. The old concrete positions are stark and weathered, but the real reason to come is the view over the Sado estuary, the Atlantic, and the beaches below Arrabida.
Treat it as a rough viewpoint rather than a restored monument. Wear solid shoes, keep clear of unsafe structures, and combine it with the beaches or coastal walks west of Setubal.