You may have stepped foot in all five boroughs, but you haven’t seen New York until you visit its smaller, lesser-known islands. Take Governor’s Island, for example. For more than 200 years, it served as a military base, but since 2003 it’s been open to the public during the summer months, delighting those who take the free ferry to explore its historic buildings and grassy fields. So if you’re looking for an offbeat outing with friends, pack a picnic lunch, meet at the ferry terminal, and set off on an urban adventure that will make you feel like you’ve left New York entirely. Play hide and seek among the ramparts of the island’s historic fortifications, imagining what it was like for the Continental Army troops stationed here in 1776. Toss a Frisbee around on one of many wide-open green spaces. And get your cameras ready, as the island offers unparalleled views of the Statue of Liberty and the Manhattan skyline. Governors Island hosts concerts and art exhibits throughout the summer, so check the schedule for cultural happenings in one of the most unique spaces in the city.