i'm working on a doozy of a project, a replica of the Alliance Normandy SR2,
The last mega structure i did was a massive castle (fully furnished, multiple floors) and courtyard, in a half and half style, making one half look "dark" or evil (that half of the castle was made of obsidian, with a cobblestone courtyard, lava falls, and a half lava moat, flaming towers and other stuff) the "light" or good side was made from pale coloured materials (wool was predominant, in blues and white), with waterfalls, the other half of the moast being water, grasslands, free-roaming animals, flowers, etc. the catle and courtyards were so big, they would not fit on the screen, no matter how far back you got.
Unfortunately I lost the minecraft save file when I formatted my computer.
