I have a huge castle I began to make on my original first world seed, I restarted the seed three times to get it look neat, it is on a small, but decent sized island, near a river, so I only had to dig one canal with water to have it fully be surrounded with it, and it is at height.

I am still far from finishing it, but I make process, on the side of castle there is an ocean where I already built a warehouse and dock/shipyard building, I got the part of a lighthouse done too, but the castle wil ldwarf all this once finished.