Castillo San Cristóbal is a fortress in San Juan, Puerto Rico. It was built by the Spanish to protect against land-based attacks on the city of San Juan. It is part of San Juan National Historic Site. Castillo San Cristóbal is the largest fortification built by the Spanish in the New World.
The trail is located on Road 988, which is a left turn just a little after El Portal Visitors center on Road 191. There is no trail head sign, but you will find the trail on the right side of the road, at KM 3.5, which is just about ½ mile after the river bridge. There is no real parking area. Just pull off to either side of the road. This short trail (about ½ mile) is an in and out and takes about 15 minutes to walk one way. As you will notice, this trail is lower in the forest than the other trails, so you will see different types of vegetation. Things we noticed were lots of heliconias and gingers, breadfruit trees (of the Mutiny on the Bounty fame) and philodendrons climbing on many trees. You will see fewer of these things as you walk on trails higher up the forest. This is pretty and there is a little pool there, but KEEP GOING! The prize is a little further on.