The Underground Booty Squad
On the west side of the river, opposite the Brewery District, there are several sandstone maze caves. The caves are described following along the bluff from southwest to northeast. The cliff between here and downtown used to be riddled with caves, but most of them have been sealed off or filled. Most of these caves have large tunnels ranging from 10' to 20' wide and high.
Echo Cave is the first cave along the bluff, named for an echo chamber that is walled off from the rest of the cave by a bizarre cement wall. However, there appears to be no passage to the other side of the wall, so it is a mystery how the chamber was accessed before they built the wall, or why it was built. The rest of the cave is a small system of dead-end wide passages about 20' tall.
Hobbit Hole Cave is a small crawl passage that was probably dug by local kids, about 50 feet long, with an exit at either end.
Horseshoe Cave is probably the most interesting of the currently accessible caves in the park. It is a maze of amorphous (non grid-pattern) passages about 15' high with three entrances. One entrance, known as the Stairway to Heaven, is a very steep staircase, or more accurately, series of footholes, leading to a hole in the ceiling high up on the bluff. There is also a hole in the ceiling in one of the rooms in the middle of the cave.
This cave (I don't know the names of the rest of them!) has two entrances connected by a long, curving tunnel. About halfway down the tunnel, there is a steep staircase similar to the Stairway to Heaven, except that instead of going outside it ends at a crawlway that progressively gets lower and muddier with no end in sight. One entrance to the cave, and a network of side passages near it, are filled with rubble from the old high bridge. This rubble is very dangerous because it's easy to trip or get a foot caught between the re-bars, or even poke an eye out.
Another small cave filled with bridge rubble connects at the back to a neighboring cave with no front entrance that is also filled with bridge rubble.