Located in Orange County, New York, the William Brien Memorial Shelter can be found at the junction of the Appalachian/Ramapo-Dunderberg Trail and the Menomine Trail atop Letterrock Mountain.
Originally known as Letterrock Shelter, it was built in 1933. William Brien, known naturalist and first president of the New York Ramblers (1923), died on October 12, 1954.
In his will, William Brien left money to build a new shelter in the park. The shelter was built in 1957 at Island Pond, but because of vandalism, it was demolished in 1973. The Letterrock Shelter was then renamed in his memory.