Tiffany's Original Diner, Saint Louis

Aside from a few hours on Sunday, the neon Open sign hanging at the entrance of Tiffany's Original Diner never powers down. This old-school, cash-only diner–which claims to be the last St. Louis 24-hour diner open on the historical Route 66–keeps its doors open 'round the clock the rest of the week, luring customers with the promise of burgers, and hearty breakfast dishes.

That's been the scene here since 1960, when Tiffany's first opened its doors. One step inside, and you might feel transported back to that era: red stools line a long counter, dishes clang in the back kitchen, and a jukebox—with a meticulously assembled and proudly "Bieber-free" catalog—cranks out classic tunes. Every other Monday, performers stop by so customers can take in live music and the jukebox can head home to see his wife and kids. On your way out, feel free to borrow a book from the honor-system library, or leave an old paperback behind.