Governor's Island is just south of Manhattan Island South Pier. The ferry will arrive in five minutes. It's free before 11 a.m. on Saturdays and free after 11 a.m. for three dollars. There are two fortresses on the island. One is round near the upper wharf. The other is a sinking fortress in the northeast of the island. On the fifth corner, there are trenches outside. The house inside the fortress encloses a square building. The island also has a good view of the Statue of Liberty.