As an old school Dungeons and Dragons player, I've always had this one in the back of my mind for Minecraft. There are plenty of classic D&D sets you could build (Castle Amber, Tomb of Horrors, Barrier Peaks, etc.) but the Keep was the first adventure many of us played, the first location we explored, and one of the first modules that TSR Games published. I know I'm not the first one to attempt this particular build, but here it is...

Here is my take on the castle compound from The Keep on the Borderlands, first edition Dungeons and Dragons. By necessity, it's fairly large, but I tried hard to keep all of the individual parts compact and efficient: villager size or "Steve Size" as I've heard it said. I made extensive use of the 2x2 spiral staircase and tried to generally limit room height to 3 or 4 blocks.

The castle itself contains all the individual elements from the original adventure, including:

The Main Gatehouse to the lower bailey

Another Gatehouse to the upper bailey

Stables/Warehouse

Blacksmith/Armorers Shop

Bank

Provisioners Shop

Traders Post

Travellers Inn

Tavern

A row of single story apartments

4 more Apartments in 2 story buildings

A Guild House

A Chapel

The Keep structure itself: I tried to stay true to the map that came with the original adventure module (I included a copy in the images) and, at the same time, make it somewhat architecturally sound. I primarily did NOT want the top portion with the Castellan's Chambers to simply be setting on the stone "roof" of another hollow stone building. So, I first designed The Keep as a twin turreted tower house with arched openings, then added a reinforcing wall around it for the second tier, then built on a half-round front section as an addition, and finally added on the two smaller half-round guard towers on the backside.

I did the Keep first, then build the rest of the Castle around it to try and keep everything to scale. There are multiple towers, each with beds, armories, and private quarters for the captains. Each tower corresponds to one of the locations represented on the map from the module. I cooked up a mountain top with World Painter to fit the dimensions of the castle.

This is nearly finished. I'm really just adding a few last details but this build is more or less done. Feel free to explore and use whatever is useful for your own adventures. As with anything else, if you use part or all of my build in a public setting, just give me credit for my work. Thanks for looking. This build gave me a chance to experiment with some different ideas, I hope my journey here helps to inspire ideas for your own builds.