This Castle Plan is brought to you by the Imaginary Castles Web Site at Dream Castles If I had a lot of money I would build something like this. -- A.P.
My Castle
As a devoted castle fan, one of the first things I'd do if I won a few million on the lottery would be to build my own dream castle. Location not important as long as it is in a temperate climate that has seasons of the sort you find in the British Isles. The settings shown here are conjectural, but the castle would be located on an ait in the middle of a small but constantly flowing river, with forest to the east and pasture lands to the west. On the north side there would be a formal garden and also an apple orchard (or perhaps pear trees), with a gazebo and a 'secret' underground vaulted chamber in case I wanted to start up a witch cult or something of the sort. To the south would be outbuildings, such as a stable, bakery, brewery, machine shop and farmstead, depending on my interests at the time of construction -- maybe all of them. There would be at least 100 acres attached to this holding, on the west side of the river, where a stone-arched bridge would lead from the ait to the nearest village or town (at least 200 feet of forest on the east would be included too, to keep the condos at bay). Note that the plan shows old-fashioned garderobe chutes draining into the river; this would not actually be the case, as all plumbing will be modern. The outbuilding area might include a Turkish bath-house, swimming pool, tennis court, or whatever, but don't bank on it.

Ground Floor
Ignore that stuff about guard rooms -- this is not to be a military castle. References to the garrison on this site apply to 'public areas' such as guest rooms and museum-like exhibits (I will have a huge collection of various esoterica I fancy). The guard hall shown here will be an estate office. The bar, of course, will be just that, with dartboards and all that in the English pub manner, and the Garden Room will be a parlor of some sort. Take the Great Hall to mean the dining room, but it will also serve as a music room, since it is two stories tall and has a minstrel gallery and even a projecting pulpit over the entrance lobby for speechifying and for soloists. Naturally, the kitchen wing will have up-to-date equipment, but will at least appear to be medieval. All the freezers, furnaces for central heating, etc. will be in the vaulted cellar. Four spiral stairs connect (a) the 'service wing', (b) the guest suite and minstrel gallery (and butler/housekeeper quarters, since only a married couple will be engaged), (c) the keep tower rooms and other bedrooms, and (d) the guard rooms. A square 'grand stair' leads up from the pub to the gaming room. The well in the paved courtyard is for show, since of course this place will have full indoor plumbing.
Upper Floors
West side: first floor, the game rooms (casino?); second floor, the ladies' and children's area (if grown up, then their suite).
East side: the butler/housekeeper suite, entrance to the music gallery and pulpit, and above that, the guest suite.
North side: first floor, library and upper area of great hall; second floor, the mistress of the house (including private bath), and also secondary bedrooms.
Top of Keep tower: the master bedroom.

Gatehouse Front
Guard's bedroom is a guest room, and the Armory is a trophy room. The men's and women's quarters are servant bedrooms (probably no more than two in each, if not just one). Castellan's room is where the permanent caretaker of the castle will reside. Muniment room will contain anything from a butterfly collection to a scriptorium. Who knows what the 'Lab' is (depends on what I'm into when this place is finished -- but it is my private mad-scientist room).

Parapet
A wall walk runs around the castle, connecting with the keep tower at east and south (the latter entrance leading out of the owner's bathroom!). At the four corners are a bartizan, two round turrets, then the gatehouse turrets, and a square 'watch room'. The front side is machicolated, meaning that the parapet projects beyond the wall, with murder holes looking down over the gate.
Miscellaneous
The Keep garrett is just a store room for old furniture and other junk, including old clothes. North face of the Keep is a parapet with a conical-roofed turret. Top of the gatehouse has a sun terrace, a caphouse for the spiral stair, and two turret rooms. A roof garden can be located here.

The Undercroft is the most noted and distinct if least visible part of the castle. It is a vaulted stone chamber some 20 feet below the surface of the garden, with ventiliation shafts leading up into the garden wall but otherwise unlighted -- can be used for anything ranging from chapel, through ballroom, to cellar. Meant to be a version of the famous 'Goblin Hall' at Yester Castle in Scotland. (This may not actually be built, depending on the bedrock foundations of the site, or the risk of flooding.)