I'm asking as I grew up around these and would love to build one myself, but I need some more information. So could anyone help me out?

Like this or This - is that concrete on top? or This other shot at the walls - not the finest work :P or This - I see this design a lot

A lot of the photos are rather fancy. I'd just like to learn more about them, and generally how I could build something like it - but without having to hire lots of people or spend an exuberant amount of money. I mean if I ever did this project, I could hire someone for archers or windows or whatever, but building a wall I'd like to think I could do myself! And I realize these have mortar and aren't the stacking rock walls, though I don't know where I'd get enough stone for those. I'm told Blue Fieldstone works well but... it doesn't look like these rocks.