Good question... I asked my friend but he didn't know. It's kinda weird, on the edge of Almada there is a bit along the side of the water where a number of former warehouses etc have been converted into bars and stuff, but if you walk further and further they stop being bars and then they get more and more run-down and you come to what seems to be almost an abandoned village. Some of it seems residential (think that one of the pics had a bath in it) and there are tiles on some of the stairs that looks as though they belong in a house... but at the same time there are what look like big tanks and that weird wooden battering ram. There are a number of factories along the side of the estuary so it could be some sort of abandoned factory... or maybe something where there was some kind of industry but also a couple of residential bits for people to stay overnight or whatever. Actually I'm gonna look it up. I think it's been abandoned for quite a while that's for sure, they are seriously being eroded by nature. Apparently they used to have parties there at one point predictably enough.
Near Povoa on this side of the river there is a huge abandoned industrial spot... that's clearly factories or warehouses or whatever, I think they just moved that industry elsewhere. The one by Almada is more intriguing cos the buildings are smaller and harder to categorise.