Australian "anti-landlord" activists are sharing information on empty properties across the country for squatters to take over and potentially steal the deeds from their original owners. Jordie van den Berg, also known as "PurplePingers," has been posting the addresses of homes he has staked out in Victoria, New South Wales, and Tasmania. Van den Berg
Basically if you inhabit and maintain an abandoned property for some number of years without the owner complaining you get ownership rights. It's why all the crumbling unused mansions in Kensington owned by Saudi princes as speculation have 24 hour human surveillance.