[imported_Jiraiya]

It took place in a custom made area where several waves of monsters spawn (increasing difficulty) and then a final boss spawned in the middle by a 3 storey tower so you could go and bank your drops here and also to heal up. The boss had some nice drops on him and dropped like 50k-100k of gold spread all around him in piles of about 500gp.
There were 2 or 3 different sets of guys that could come; 1 was arachnids and those dudes, another was lizards, and I don't remember the other sets but it was really fun and sometimes took like 2 hours to get to the final boss. Also, once it was started I dont think the staff had to baby sit it because it was mostly automated.

Its called monsterbash here. For like 2 months it was the only event hosted.

I was thinking more along an area that you go to whenever you want, not an event.

I'd probably be for making 1 town of the game perma DM town like that. But there was some pretty good arguments against it if I remember right. Mainly centered around PvP not being free to participate in all the time. Skillcaps dont really work here, that just severely limits the amount of players because of how easily you can buy 2k worth of skills the first 10 minutes of play. Thats how the deathmatch auto opening every 4 hours came about, everyone gets a chance to participate no matter their timezone, and its not perma free pvp. Same sort of deal as the free duel box area, opens up only once in a while to give players a place to practice.