[SkyPilot]

Interesting. There was a great show on the History Channel last night (Modern Marvels) about the Roman Coliseum.

[mainepatsfan]

I saw it. An impressive bit of engineering even by today's standards.

[wildbill]

The Colisseum was built with concrete which was developed into a final form as a construction material by them. However, the secret of its composition was lost during the Dark Ages.