Welwyn Preserve, Natural preserve in Glen Cove, New York, US.

Welwyn Preserve is a nature reserve on Long Island's North Shore in Glen Cove, New York, made up of woodlands, salt marshes, and butterfly gardens. A network of walking trails runs through the property, connecting these different habitats.

Welwyn was the estate of Harold Irving Pratt, an oil industrialist born in 1877 who died at Glen Cove in 1939. The Georgian-style mansion was built in 1906 by Babb, Cook & Willard and renovated in 1920 by Delano & Aldrich. The property is now owned by Nassau County and run as a public preserve.

The mansion, Welwyn, has housed the Holocaust Memorial and Tolerance Center of Nassau County since the museum was founded in 1992 and opened in 1994. Holocaust survivor Boris Chartan was its first chairman until 2003. Visitors enter the 1906 Georgian-style building for exhibits and educational programs.

Dogs are not allowed anywhere on the property, so it is worth keeping that in mind before heading out. Opening hours differ between weekdays and weekends, so it is a good idea to check them in advance.

Abandoned greenhouses with concrete basements on the property were once used as a training facility for the Nassau County Sheriff's Department. These hidden structures come as a surprise to many visitors walking through the woods.