This site is closed due to the government shutdown and will no longer offer Ticketed tours during OHNY Weekend.

Castle Williams is a circular defensive work of red sandstone on the northwest point of Governors Island in New York Harbor. It was designed and erected between 1807 and 1811. Designed by the Chief Engineer of the US Army Corps of Engineers, Lt. Col. Jonathan Williams, for whom the fort is named, it is considered a prototype for the generation of coastal fortification that followed its construction. It is one of the earliest examples of a Casement style fort and a key aspect of the harbor defense system created in the early decades of the 19th century to protect New York Harbor. Tours of the interior will be led by a National Park Service Ranger.

The lower level of Castle Williams is wheelchair accessible. However, the tours of the interior include 3 flights of stairs, and there is no elevator in the historic structure. All visitors on interior tours must stay with and follow the directions of the Ranger or NPS affiliated volunteer.

Governors Island is accessible via the NYC Ferry (multiple routes) or the Governors Island Ferry departing from 10 South Street, Manhattan. Ferries depart promptly as scheduled, so please plan your route and travel time carefully to ensure a timely arrival. This reservation does not include your ferry ticket. You will need to purchase a ferry ticket to board the Governor's Island ferry. You can purchase ferry tickets online at https://www.govisland.com/plan-your-visit/ferry or in-person at the ferry terminal kiosk.

Late arrivals will not be able to join the tour once the group has entered the Castle. Plan to be at the Castle to check in before the tour begins.

Children are welcome accompanied by an adult. All persons attending, including children, must have a ticket.