Guild v guild castle battles

I've heard stories back even to Ragnarok Online about guild v guild fighting over castles in big battles. Are there any current mmo's that allow for something like that?

Guild Wars 2

GW2 is pretty much the go to for RvR gameplay with 'Castles'.

Maps are the perfect size to find fights and for organized guilds of different sizes to conduct raids (which has given it alot of legs compared to other games like ESO and AA). It's very easy to get into with seamless combat on different scales, but tough to master because communication is half of the gamemode. Just be sure to find the right server and get involved as Mumble/Teamspeak usage is quite vital, espcially if you want to participate in an organized guild.

How can I go about finding that?