Drawbridge

Tom raced across the drawbridge.

The drawbridge is raised at nightfall to prevent monsters from reaching the fort.

Raise the drawbridge!

We crossed a drawbridge.

Near-synonym: bascule bridge

I might jump an open drawbridge, or Tarzan from a vine / 'Cause I'm the unknown stuntman that makes Eastwood look so fine

drawbridge mentality

I looked at her with wide eyes, and the drawbridge of her reserve fell instantly.

"Yeah, some people have a drawbridge mentality,” remarks Barry.“They move to an island and then they think that nobody else should be let in after them. […]

And He gave me the steps I needed to take to let down the drawbridge of my heart again.