It used to be that just the road was closed. But in 2005, the FAA chose to close the radar station at Pico del Este, high in El Yunque, Puerto Rico’s national rainforest.
The station had been monitored 24-hours a day until it was closed, and the location is now being overtaken by nature. The buildings are deteriorating from time, humidity and rain. Many urban/jungle explorers visit the site now, and it has been a favorite for geocaching.
Update: As of September 2014, the site is being actively dismantled and removed by the FAA. You are very likely to encounter workers and/or government employees while attempting to access the site, even on weekends; expect to be told to turn around at the very least. It’s unknown to what degree the structures have been demolished.
Update: Jan 1st 2015. The smaller radar dome is about 50% demolished while the larger one is still intact. Recommend visiting on a holiday as we had no interference. Note that it’s about 2.5 miles from the gate and mostly uphill, so bring water..