Fort Union is actually the site of three consecutive military forts, the first being established in 1851 and the the third being abandoned in 1891. The National Monument was established in 1956 to preserve the historic ruins. The park offers youth programs, self-guided walks, interpretive programs, and a visitor center and museum.
The National Monument is located 94 miles south of Raton, only eight miles off of I-25. It’s well worth a visit if traveling that direction from Raton, and makes a nice stop if driving the scenic loop from Raton to Mora, Taos, Eagle Nest, and back to Raton.
Official website: http://www.nps.gov/foun/index.htm