Fort Constitution's main gate! The pointy wooden stakes that represent the fort's front door is the portcullis. The original Fort Constitution had a pair of heavy oak doors with loopholes for sniping at unwanted visitors, which would have been behind the portcullis.

The portcullis that we're looking at was restored by the New Hampshire Daughters of the American Revolution in 1974, in commemoration of the capture of the fort by New Hampshire patriots in 1774. Which of course was actually the capture of Fort William and Mary, the British fort that was replaced by Fort Constitution, but whatever. Can't argue with a new portcullis.