If only all 2000-year-old ruins could be so well preserved! The eruption of Vesuvius in 79 AD may have destroyed the lives of the people living in Herculaneum, but, by carbonising organic materials and then burying the entire town in lava and ash it has preserved it for us in almost perfect condition.
A short ride (about 20 minutes) on the circumvesuviano train line will take you from the central station in Naples to Ercolano Scavi station. From there it's a short walk down the hill towards the sea to the ruins.
Plan on spending several hours here and taking lots of photos. I'd filled the 512 meg card in my digital camera before I was half way around!
The buildings are so amazingly well-preserved, many are still fully roofed, and decorated with vibrant frescos and mosaics. You can truly get a sense of what life was like for the people who lived here.
You'll need to provide ID as a guarantee and hand over a fiver if you want to get the audio guide, which also entitles you to a map. If you don't rent the audio guide you don't get a map at all, however, the guide is almost essential if you want to know what the various buildings you're looking at were used for. There's a section on each of the buildings and a few extras which you can listen to to get more information on a particular topic.
Some buildings which are described in the audio guide may not be open to the public when you visit, which is a shame, but the site is undergoing on-going preservation work so this is inevitable really.