John 14:1 - 11
ESV - 1 Let not your hearts be troubled. Believe in God; believe also in me. 2 In my Father's house are many rooms. If it were not so, would I have told you that I go to prepare a place for you?
For follow-up discussion and general commentary on the topic. Comments are sorted chronologically.
It will be the city we live in that is measured out in the book of Revelation, or New Jerusalem.
However, I prefer the King James translation, it states many Mansions, not rooms.
I just don't think living in a room for eternity would be Heavenly... A MANSION on the other hand. Time will tell though.
And the size of this New Jerusalem will hold Billions of saved souls.