Different on the inside is the fourth level of Chapter 4.
Amy Pond: It certainly is... different on the inside.
Eighth Doctor: Amazing, I love it!
War Doctor: Not another one like this.
Twelfth Doctor: All of us here, together, our timelines are collapsing in on each other, destabilizing the spacetime around us. We have to be very careful.
Tenth Doctor: To the library!