The Hall of Heros is the final section of Hero's Ascent (in the Battle Isles). Heros Ascent is essentially a bracket where each team you successively defeat moving you closer to the Hall. Once in the Hall, you fight for Favor of The Gods for your individual territory, along with some pretty sweet drops for your individual team if you win.
You need to read up on Heroes Ascent on Guildwiki to get the general jist of it.. It's pvp based, not like the story you have been following around Tyria.
there is also a "Hall of Hero's" Player Versus enviroment presented as the last level of the "Tomb of Primeval Kings"...which is near Glints Dragon lair in Tyria.