Stonecutters' Tunnel

The Stonecutters' Tunnel is a secret tunnel for members of The Stonecutters to drive through when they are stuck in traffic and need to get to work. It is guarded by a boulder and filled with classical paintings and music.

Non-canon
In "The Simpsons: Hit & Run" the tunnel is located next to Burns' manor and leads into the Nuclear Power Plant. by plays in the background.