i was at an adopted site like that in valencia, which a collective had nicified and ended up fighting the municipia who of course realised they wanted it after allYeah easy to say "get in your garden" but I don't know anyone who has one to get in.
Allotments seem to be big here.... although you can't really call them allotments, as I suppose that implies you were allotted it by someone or something; as far as I can tell if there is an empty bit of land then people just put crappy fences made of old bits of plastic around it and take it. Kinda like a claim in the old west. Once they've got the bit of the land they tend to strew it with rubbish, leave a dog tied up howling mournfully all day and all night... and possibly plant a couple of potatoes.
Sometimes they build houses, there is a bit on the edge of Lisbon which is a kind of illegal semi-shanty town.