How can you climb onto a roof without leaving the ground?
A new piece of art in east London lets visitors see what it would be like if they had the same climbing skills as Spiderman.
Visitors are told to lie on the house painted on the ground with mirrors positioned overhead.
Their reflections then give the impression they are standing on, hanging off or climbing the building.
The fake house was designed by Argentinean artist Leandro Erlich.
The project, called Dalston House, will be open to the public until the start of August.
The house isn't real and is a specially designed piece of art, so don't try and climb one yourself.