This group of caves is several hundred feet above the floor of the canyon. It's about a 30 - 45 min. drive from downtown, depending on traffic and if you get lost. It was developed as a tourist attraction by the Monterrey Lions Club after WW II. For decades there was a traintrack that ran up the side of the mountain (portions of it almost vertically), but just a few years a Swiss firm was hired to install a cable tram. So now you get into the gondola and silently swish up to the entrance. The admission, including the tram ride, is about $5 U.S. If you want to walk up they take about $2 off (It takes about an hour to walk up).
The tour itself takes about 45 mins. and covers over a mile. Some of the inclines are steep and there several sets of stairs that are more like ladders, so bring good walking/hiking shoes. The tour of the caves itself is not for the physically handicapped!
You should definitely pay a visit. The tour guides are hilarious, the caves are pleasantly spooky, and the view from the top of "the Sleeping Indian" mountain is gorgeous.