Sundial in a tunnel

What is this beautiful thing that we've found?
Is it a sundial underground
Or just a building falling down?
I'm so happy i could scream,
But when you said i dream everything's fine.
What is this terrible thing that has gone away?
Is it a beautiful day
Or is it just ok?
You're so happy, so why am i so sad.
You prefer tomorrow to the times that we once had.

What is this wonderful thing we once had?
Is it baby singing dad,
Or driving each other mad?

What is this beautiful thing that we've found?
Is it a sundial in a tunnel
Or just our home coming down?