Identify the main characteristics of the Greek/roman underworld

Answer 1

http://www.gods-heros-myth.com/godpages/underworld.html

http://voices.yahoo.com/where-hell-greco-roman-myths-underworld-15670.html?cat=34

http://www.roman-colosseum.info/roman-gods/roman-underworld.htm

http://en.wikipedia.org/wiki/Hades

http://ancienthistory.about.com/od/greekdeath/a/092909Afterlife.htm