As mentioned previously, Mt. Vesuvius looms over the city of Naples. Its last, really spectacular eruption was, as most of you know from history class, in AD 79, when approximately 200 metres of the top of the mountain vanished.
The city of Strabia (a Roman summer resort on its hills) was completely destroyed by lava flow. Herculeneum, another summer resort city of ancient Rome, was also buried and burned.
Archeologists are fortunate in that Pompeii missed most of the actual lava, but was buried under 25 metres of hot ash.
In the late 1700s, archeologists started digging at the site where Pompeii was rumored to have existed. And they found treasure upon treasure, both in objective wealth (unfortunately a lot of the spoils vanished into the clutches of collectors of the time) and in subjective knowledge. Above is the temple of Jupiter. The restorers have made a concerted effort to show what actually existed, and not try and hide the newer materials. The light pieces are original, the dark ones are reproductions.
The forum, or rather its portico.
City walls. Paving stones at the sides of the road are original. Road surface is volcanic.