in the BBC television programme "Dr. Who", a vehicle used by the Doctor to travel through time, that looks like a blue telephone box from the outside but is like a large spacecraft on the inside

something that is much larger inside than it appears to be from the outside

Many a home is a Tardis, looking small outside, but spacious within. 很多人的家就像是一个“塔迪斯”，从外面看小，可是里面却很宽敞。