When is a henge not a henge?

Civilisation 6 came out about a week ago. Civ, as it is known, has a massive following because it is the most sophisticated game of its type. Yes, you wage war with archers, cannon and nuclear weapons, but you can also win a diplomatic victory, seal trade agreements, found religions, cultures and Wonders.

One of these wonders is a henge. And that is where the confusion starts.

Because when we hear the word 'henge' we automatically think of Stonehenge. I mean, why wouldn't we, it has the word 'henge' in it after all. 

And yet, it isn't a henge.

Confused? I'm not surprised.

OK - this is really simple.

A henge is a prehistoric monument created for ritual purposes, and as if to underline these ritualistic motives, it is purposely built the wrong way round.

Think on this - you build an earthwork structure to defend yourself. You want to make life as difficult as you can for an attacker. So, you build a ditch and a bank. Defensively you build the ditch on the outside, and the bank inside because then any attacker coming from outside has to descend the ditch and then scale the bank.

Let's say you dig a ditch around the outside of your settlement to a depth of 2m. The spoil goes inside the ditch, into your settlement, and you use it to create a bank. Anyone attacking you faces a ditch and a bank. The ditch is 2 metres deep. The bank is 2 metres high. That is a combined difference of 4 metres: 2 metres down, climb back up those same 2 metres, and then scale a bank of 2 metres. That's defensive.

Now reverse that. You build a monument. You build a ditch 2 metres deep. You use the spoil to build a bank, outside the ditch. Anyone coming to your monument goes up a bank of 2 metres. Then they descend 4 metres, easy, and then up another 2 metres. The downward run would carry them most of the way up the 2 metres bank. Not defensive. 

So, a henge is a reverse of a defensive ditch earthwork.

And just to be sure, let's have a look at first Stonehenge:

And now Avebury, a true hengiform monument: 

See the difference?

Now you know conclusively what a henge is.