The following is a step by step guide to building a built up area (BUA) based on the Viking fortresses during the dark ages for DBA.
In the style of the Viking forts during the dark ages, cut a round 18cm by 18cm piece of MDF out of the MDF sheet. Bevel the edges to make them more natural looking. Then cut out a piece of styrofoam into a circle shape slightly smaller than the MDF. The outside of the ring should be straight up and down, the inside should taper upward.
Construct the front gate out of thin, sturdy card. Basically, cut three rectangles out of the card and then shape merlons and crenelations into the top. Before you glue it together, use your hobby knife to carve slots to define the wooden planks. Then, cut a strip or two to use as support planks and glue them horizontally onto the walls.
Cut a narrow strip of card the thin card to make the outside wall. Carve the planks into the surface and then glue it around the foam. Cut out strips and glue them to the back of the wall to make crenelations.
Now it is time to build the long house in the center of the fort. Build the basic walls using the 1.5mm card. Then put planks on the outside walls of the structure with strips of thin, packaging card. After the walls are made, make the roof the same way, then thatch it. There are many ways of doing miniature thatch, for more information see my Thatch Roofs article. The method I used for this project was the binder's twine method.
To finish, put down some sand and then paint the while thing brown. Highlight the sand with light brown. Highlight the wood parts with grays. Then put the various static grasses down heavy around the outside of the walls and sparsely on the inside.