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From ground level it can be difficult to make out the traces of a ditch here or a raised bank there.

But climb into an aeroplane and view them from a few hundred feet up and it's easy to see these early fortresses and settlements in all their glory.

We've obtained this series of stunning aerial photos of Shropshire's pre-historic sites from the archives of the Clywd-Powys Archaeological Trust.

They show a selection of selection of sites as most of us never seen them - and in a way that reveals the skill of the Bronze and Iron age people who built them.

The Berth, near Baschuch

Bronze Age

Shropshire's earliest man made remains date from the Bronze Age, which spans the period from about 2400 BC to 700BC. Most are ritual sites, or mark the location of the grave of an important person.

Many are burial mounds, such as the stone-built cairns on the Stiperstones and other hills, or earth-built barrows elsewhere.

Shropshire's two stone circles also date from this period, as do a series of ditches across many of Shropshire's upland areas, known as cross-ridge dykes.

Iron Age

In the Iron Age (700BC to 43 AD) the emphasis shifted away from purely ritual sites and for the first time traces of settlement can be found.

The most spectacular of these are the hill forts, of which there are more than 50 remaining in Shropshire.

In a nutshell, a hill fort is a settlement on a hill defended by ramparts and ditches of varying complexity. Typically, there are exceptions, such as The Berth, near Baschurch, which is built on flat ground, although it still commands the surrounding area.

Old Oswestry

Hill forts were, by their nature, exposed and inhospitable, and historians are divided as to whether they were permanently occupied or just used in times of danger.

To start with, none had their own water supply, which would have been a pre-requisite to surviving any sort of prolonged attack.

Whether or not hill forts were occupied all the time, they certainly weren't the only areas occupied by Iron Age communities. They were just the most visible.

Much of the population lived in small defended farmsteads or unenclosed settlements, but little trace is left of these. Many may even be the basis for some of our modern day settlements, just as many hill forts were replaced by medieval castles..

But one survives at Black Knoll on the Long Mynd, where the remains of an ancient settlement can clearly be seen in our aerial photos.