Sendai Castle was built close to the river to use the river as a natural moat.

It stood atop a rocky promonitory and was protected on its landward side by a marshy swale that formed a natural moat.

This confluence provided Roman soldiers with a natural moat to protect one of the forts, which are generally named after Greensforge.

The U gave the castle what amounted to a natural moat over nearly half its circumference to supplement the one its builders had dug themselves.

Later a major stronghold for border protection, Nizhny Novgorod fortress took advantage of a natural moat formed by the two rivers.

Before you cross this thigh-high, and in places rocky-bottomed, natural moat, you pass chunks of black, volcanic rock.

There was a natural moat there now, a gap between most of the other ground troops and us.

It was a great town, surrounded by a Cyclopean wall of boulders, about which the river ran on every side, forming a natural moat.

The river, cutting through the naked desert, split on that great rock and passed about it on either side, forming a natural moat.

It commands its surroundings from a cliff 40 metres high, with the river forming a natural moat around it.