Located About 36Km from Monterrey, off the Saltillo-Monterrey highway are the magnificent caverns - Grutas de Garcia. On the outskirts of Monterrey, after crossing Santa Catarina, keep watching for the board pointing right which reads "Grutas de Garcia". After turning right and crossing the industrial area of Garcia, Nuevo Leon the road becomes narrower and passes in the canyon. One can either trek all the way till the entrance or take the teleferico, the cable car. The trek approximately takes about 30 minutes (less if you're in good health) and costs 45 pesos while the cable car takes about a minute and costs 65 pesos.
The view of the valley from outside the cave is picturesque. The cave has many stalactites and stalagmites formed millions of years ago and the climate inside the cave is very pleasing, especially during summers. The cave approximately takes about an hour and a half for traversing. There are guided tours if you wish but I felt it was useless looking at the way the guide was explaining to others. The last guided tour starts at 5 in the evening and one has to be inside the cave before that time.
A note for photographers, the cave is dimly lit in most places and a tripod is a must carry if you don't want your photos to be blurred. Don't carry any of your telephoto lenses for those will be of no use, just take one ultra-wide angle lens and that should suffice for all the photographs.