This was a very well entrenched location utilizing both natural and man-made barriers.

Hadrian was a gifted administrator who set in place a policy of creating natural or man-made barriers at the empire's outer limits.

I rooted for his survival, willed him to stay safe and cheered him on as he crossed yet another man-made barrier.

He used his electric torch sparingly to investigate the inside of that tall man-made barrier.

In the isolation of the last days, in stress and extremity, all man-made barriers had fallen; they were two boys the same age, friends, bredin.

Others have called, at the least, for broadening existing man-made barriers, most of which are here in Arizona and in California.

The Wall itself is merely a man-made barrier, sharing the properties of the space in which it lies.

The artificial, man-made barrier of religious beliefs is higher and wider than the Berlin Wall ever was.

Known simply as 'Fish Lake,' the man-made barrier was approximately 30 kilometers long and 1,800 meters wide.

Other options might be natural or man-made outdoor barriers or buffers.