The atmosphere to these are great.
The towers build out of tiny pieces, yet the final results look very coherent. I wonder how you managed that.
Each building is made of 32x32 px block, each block is animated, when a block pass a certain point on the animation, it spawn a new block or a roof and also sides blocks. There are also "bridges" block who can spawn between building with a certain gap space. Also the maximum height for the towers is specific to each layers, at a certain point, a roof must spawn.