Camelot Unchained ("DAoC 2") player building + intro
Big structures will matter for economy and control of conquered territories. Building is 100% free form (think: Minecraft on steroids) and this is how it looks in alpha tests, video by one of players:
...many, many hours later:
He made this by C.U.B.E. building tool and round / cylindrical shapes & wide choice of textures are yet to be added. Buildings can be destroyed - unless built offline or in starting zones BUT there will be siege windows (time for destruction) and it should take big number of players and siege engines.
The game is Camelot Unchained, "Dark Age of Camelot 2", PvP / crafting / building MMO by Mark Jacobs. Or you can check it's IGN Wiki for quick intro and more pics + videos. Access now is not too cheap, but beta starts in a month or two (?) and they should have open beta (free tests) in 2017.