Went on a tour and had a phenomenal tour guide. He was super informative and a great sense of humor. Crazy they built such an incredible castle to withstand cannon shots. It totally worked but then they never actually got to use it in a war and it was used as a military prison. The castle was made of sandstone which just compacts when hit. The outside wall was built separately from the main wall so if one got hit and was too collapse it didn’t destroy the entire fortress. It was built in a circular shape. From sea it appears straight so if a cannon from a boat tries to hit it if they don’t hit it straight on there is a greater chance they would miss. Everyone thought the builder was crazy but apparently he had some pretty darn good ideas.

i liked the story of putting the first american flag over the walls of this castle after great battle occurred around this place and how the first american anthem was singed here at down time. i was luck to see this flag few days later during my visit to the DC i recommend to visit these place together to connect the dots and to get full picture

Incredible place. Rangers are very helpful and the tours are excellent. A lot of history here and some fun stuff to look at as well. Tours are free but kids may get a lil bored as they are mildly long.

Great experience on a warm sunny day. So much history to explore at this Ice-cream Cone shaped Governor’s Island. Castle Williams has an eerie feel with prison windows overlooking the Hudson. Ample picnic coots and happy trees to laze under. A must go for families and art enthusiasts to view the numerous arts displays and poets rendering their feelings from porches of the old villas.

If you’re just passing by, it’s okayy. While the informative signs are interactive to keep visitors engage, the castle itself isn’t anything special, lacking visitor access to more desirable viewing platforms at the top. Definitely go on a tour if you’re truly interested in the history.

It was a fort, it was a prison, and now it's a historic place to visit by when you go to Governor's Island. Castle Williams is officially listed on the National Register of Historic Places. You have to go on a guided tour to get to the roof of the castle. Be prepared to climb three flights of stairs. We talked to ranger about the tour but didn't go on one. She warned that young children may get bored quickly on the tour and it gets hot on the roof.

It's a really cool place, definitely worth a visit.

It was closed when I visited there. But around this place/island is awesome!!!

Great place to experience.

An old fort with lots of signs and some interesting history. There is usually some staff around if you have questions.

Great views of lower manhattan and some great history in this fortification. Must see for any history buff.

View from the SI ferry ⛴️

I'm amazed that they Preserve this Building, love it ❤️

Nice sceneries.

An old fort where you can feel history around you. I enjoyed the miniature of the fort the most. Cudos to the art person who did it