When my children were little, I read them the entire Chronicles of Narnia series by C.S. Lewis. This passage is from the last book in that series, “The Last Battle”:
“‘It seems, then,’ said Tirian, smiling himself, ‘that the Stable seen from within and the Stable seen from without are two different places.’
“‘Yes,’ said the Lord Digory. ‘Its inside is bigger than its outside.’
“‘Yes,’ said Queen Lucy. ‘In our world too, a Stable once had something inside it that was bigger than our whole world.’ It was the first time she had spoken, and from the thrill in her voice, Tirian now knew why.”
Tirian and his forces had been fighting the Calormenes, who had been stroke by stroke herding them toward the door of a little thatched stable, 12 feet long and 6 feet wide. Inside, they were supposed to meet their doom. But when they were finally forced through the door, they found themselves in another world entirely. The door still stood there for everyone to see; but the stable was gone. They could walk around the door, which was standing brightly in the meadow, as if it grew there.