Not my first build, if fact from from it, but the first that I am willing to share. Yes, I know there are an abundance of castles already, but architecture has to start somewhere, and this is how I chose to get my start.
Feel free to rate out of 10. If you could, constructive criticism would be appreciated.

First, of course, is an overview of the whole place

The Entry Hall of the main keep

The Reception Hall, the next room in

The Chapel

The lower dining room

A Residence "Suite"
Now for the less... Opulent portions of the keep.

The barracks of the dungeon guards

The Prison itself

A bit random, but the bow-racks of one of the armories below the base barracks.
There are other rooms, of course, some are not well furnished, I know, while others are seemingly over-furnished, such as the Barracks in all parts of the castle. The basement of the keep is accessible through the Reception Hall by clicking the odd colored brick in the wall. The Porticullus' can be opened in the gate house by clicking on the top of the mechanism.
Note: The standard number of doors will not be enough. It uses a rather large number of them.
Used:
Ceiling Print Bricks by Space Guy and Killer_Whale
JVS Doors and Door Pack 1 by Trader
http://www.mediafire.com/file/zwjtzyiw4un/Theroc Fortress.bls