The historical action movie "Pompeii," opening Friday in theaters, is actually two movies rolled into one. The first film is a standard-issue gladiator picture, with our hero Milo the Celt (Kit Harington) fighting his way through a procession of increasingly scary bad guys. Milo's adventures take place in the slave pits and arenas of Pompeii, the ancient Roman city that was famously buried in volcanic ash around 79 A.D.
The second movie kicks in about halfway through, when nearby Mount Vesuvius erupts in a spectacular display that provides all that historically accurate ash. Also: pillars of fire, rivers of lava, flaming boulders, several earthquakes and even a giant Mediterranean tidal wave. What began as a B-movie gladiator flick ends as a disaster picture of epic proportions, with eye-popping 3-D effects.
History nerds should enjoy all the big-budget production values detailing the ancient Roman Empire. Before the fiery destruction, the movie depicts life at the height of the Pax Romana era -- the period of relative peace after Rome's initial expansion and before its eventual decline.
Watch the corners of the frame in "Pompeii" and you can glean some interesting tidbits -- for instance, some colosseums had a kind of partial and primitive retractable roof for shading the VIPs. Here are 10 more details about the ancient Roman empire that you might not know.