Transdimensional engineering allows the TARDIS to have a deceptively large inside. Letranger Absurde (vitreolum) has cleverly used forced perspective to build what appears to be an impossibly big TARDIS interior:
Though the rest of the build is equally clever as the camera angle, including the great Doctor Who figure, the TARDIS itself, the doors and I really like the simple but effective sewer gate.
Just to give you guys a heads-up (why do you need it?!):
http://www.mocpages.com/moc.php/398223
That is on my list. Still getting caught up after BrickCon.