Doors are fascinating story tellers, whether grand and glorious or hanging in ruins. All are keepers of secrets, and if you're curious - like me - it's a struggle to keep oneself from trying the handles on every one of them.
This one was irresistible:

I stumbled upon it while camping in the Adirondacks. Built into the side of a hill, it is virtually invisible until you're right in front of it.
What's inside?
Step past the smiling guardian and you find yourself in a cold, dank, earthen room perhaps six feet by six. Before you is a wall that is sprouting roots. To your left and right are circular metal tunnels, four to five feet in diameter. It is too dark to see far inside them. A camera flash reveals that the tunnels are shallow, holding only accumulated debris and a few dusty bottles of wine.
This could once have been an ice house or a wine cellar, but judging from the gatekeeper's armload of produce I think it more likely to have been a root cellar. Whatever its use, it was pure magic.
And then there are these:
The tall doors leading to the balconies are on the top floor of the S.J. Payne Building in historic Wabash Indiana. It was built by Sam Payne in 1989* (*correction - 1898) as a combination furniture store and funeral parlor. (Creepy to us, a common combo back then.) The town is still talking about the party he threw there to celebrate its completion.
Through those doors passed the rich and powerful, accomplished craftsmen, smiling newlywed shoppers, mourners and the ghosts of their dead.
Last and least, here's the entry to the barn next door:

It's a great old barn. But sadly, "Tomorrow" never comes.
You'll find more great doors at The Round Robins Photo Challenge.