In 2007 my brother and his then girlfriend (they are now married, don't worry!) decided that with some help from their friends they would build tree houses in Regent's Park. Now we all love tree houses don't we? These ones were big enough to hold events inside, music art, recitals and workshops. They were there for three months and it really felt like they had created a community within nature.
It was such a unique, awesome event and the great news is... they are bringing it back and this time, they need your help! As you can see from the pictures, they sourced all of their materials for free and they created larger versions of what you and I would find in the garden but with the Invisible City they have gone further. A lot further. Together with an architect (who worked on the Eden Project btw) they have created some incredible structures that unfortunately cost money.