Camelot Unchained (aka DAoC 2), player building video + intro
Building is 100% free form (like Minecraft), this is video by Necromaniak and this is how it looks many, many hours later:
He built this by C.U.B.E. and destruction should take big number of players and siege engines.
The game is PvP / crafting / building MMO or you can check it's IGN Wiki for quick intro and more pics + videos. Access now is not cheap, but they'll have open beta (free tests) in 2017.