1
First and foremost, remember that you are creating a stage for role-playing. That fact takes precedence over historical accuracy or even architectural validity. You should include areas that exist solely to be challenging, puzzling, wonderful, and dangerous. Put high balconies directly above spiked iron fences. Run high staircase with inadequate (or absent) railings. Make roofs that are peaked like spires, simply because they look creepy. Assume that a part of the house is shoddily built and heavily-water damaged, with a floor that will inevitably collapse underneath the PCs. Consider what makes each part of the house a potentially interesting place for gaming.

2
Grand houses are organized into a main section, and one or more wings. It was not unusual in the larger houses for entire wings to go unused, or be sealed up. Already by the eighteenth century many aristocratic families found it economically impossible to properly maintain their homes. It was common for one wing of the house to be luxuriously appointed, while another was allowed to become a virtual ruin. In a game like Ghastly Affair, such a neglected area might be haunted, under a curse, or even secretly inhabited by a gang of bandits!

3
A very common layout for a grand house consisted of a central rectangular block (called the corps de logis), with two perpendicular wings projecting forward. The area in front of the central block (and flanked by the the projecting wings) is called the cour d’honneur (court of honor), and will often have a central fountain and/or garden.

4
The status of the floors in an eighteenth-century Italian or English house was, from lowest to highest: basement, attic, ground floor, second story, third story, fourth story. The ground floor would house the public and entertainment spaces – ballrooms, salons, game room, etc. The family’s quarters would almost always be on the the second story, and the rooms for important guests on the third or higher. Servants would be in the basement or attic, when they were not relegated to their own wing (or a completely separate building). In France, however, ground-level bedrooms with window doors that open directly onto gardens were considered very desirable.
(Note: The first level of a house is called the “ground floor” in Modern British English, but the “first floor” in Modern American English. The British “first floor” is the American “second floor”. To avoid confusion I use the term “ground floor”, for the floor directly above the basement, and “second story” for the level above that.

5
The rooms in British stately homes would usually be given colorful names, such as “The Rose Bedchamber” or “The Leather Salon”. In France, however, it was common for bedchambers to simply be numbered – a practiced carried over into modern hotels.

6
British stately homes tended to be significantly larger than French chateaus, and have a larger staff as well. Likewise, the country estates of British aristocrats were generally larger than their French counterparts. British grand houses were often built in conscious imitation of Italian architecture (particularly the designs of Andrea Palladio), but French-style chateaus could be found everywhere across Europe.

7
Remember that any grand house, whether urban or in the country, must have a stables and a carriage house of some kind. The two structure may be combined into the same building however.

8
If you place a fireplace in a room, remember that its chimney will rise up through every floor above. Fireplaces will usually be located exactly above and below other fireplaces, so that their flues can share a chimney. Also, remember that every chimney must be supported by a pillar, or solid wall, running directly below it to the floor of the basement. Not every room needs to have a fireplace – many grand houses used large ceramic stoves instead.

9
Because the basement must support all the weight of the house above it, the rooms there must either be separated by thick walls, or include pillars spaced about 10 – 15 feet apart.

10
A room on the ground floor that is more than 50′ in length will usually need to have its ceiling supported by pillars. There will be thick walls or pillars directly below in the basement.

11
Remember to account for the swing of doors when placing them in rooms. The doors in eighteenth century houses are often much larger than those in modern homes, despite the fact that the average person then was much much shorter than the average today.

12
Corridors were not common until the 19th century. Rooms in pre-20th century grand houses often connect directly to other rooms. People often walked through occupied bedchambers to get to other rooms (that, along with the ubiquitous chill, was the reason for the curtained beds). In a time when the Queen of France had to eat dinner every day before a crowd of spectators (and wealthy people were washed and dressed by servants), little value was placed on privacy.

13
Remember to account for the slope of the roof when figuring the size of rooms in the attic. If your roof slopes at a 30 degree angle, with an attic ceiling 15 feet high directly underneath the ridge, 10 feet away in either direction there will only be 8.75 feet of headspace.

14
You do not actually need to put in separate rooms for toilets – 18th century grand houses often didn’t have any. The inhabitants relieved themselves in chamber pots that were emptied each morning by the servants. The pots were located in the bedchambers, or even in concealed spaces in the dining rooms! When there were dedicated rooms for relieving oneself they were small closets with a bench at one end, inside of which was a chamber pot that needed to be manually emptied. Only the most advanced houses had flushing toilets. Many English stately homes did not have toilets well into the 20th century.

15
18th Century houses did not always have fixed bathtubs, because most people sponge-bathed. Full-immersion baths could be taken as infrequently as once a month (although some people, notably Marie-Antoinette and Mary Wollstonecraft, did bathe daily). In Britain, baths were more likely to be located in an exterior bath house. A bathtub in a French chateau, however, was likely to be located inside a bedchamber. Bathtubs might be filled by exterior pumps worked by servants, but just as often the tub had to be manually filled and emptied. Some tubs were situated below a fillable water tank fitted with a faucet.

16
As strange as it seems to modern eyes, the kitchens would usually be located some distance from any dining room. This was so diners would not have to smell any cooking odors. Often, the kitchens were in an entirely separate building. Food was brought to table from the kitchen in covered dishes, and was seldom very hot by the time it is eaten. The fact that the arrangement is impractical and inconvenient was not considered important by architects of the 18th century (and earlier).

17
Creating an impression of grandeur and opulence was of primary importance for the architects of grand houses. Important rooms would often have one or more anterooms, whose sole purpose was to set the stage for the even more luxurious room onto which they open. When creating fictional grand house, do not be afraid to waste floor-space in ways that would horrify a modern architect.

18
Remember that a standard ceiling in an eighteenth century grand house is 15′ high, and 20′ ceilings were not uncommon. A ceiling than is merely 10′ high was actually unusually low. Rooms such as Grand Salons and Ballrooms might have ceilings that extend upwards for two (or more stories), with balconies looking down from the upper stories.

19
Both British and French-style grand houses had secret doors, but they often had different original functions. In Britain, the secret doors and hidden chambers (called “priest holes”) often originally served to hide renegade Catholic clergy, or for smuggling contraband. In France, secret doors might be built to facilitate the secret entry and exit of lovers, or just for sheer novelty. The palace of Versailles has a famous secret passage that was once used by Marie-Antoinette to escape a besieging mob in 1789.

20
Eighteenth century French chateaux often have oval and other oddly-shaped rooms whose interior arrangement cannot be be guessed from the exterior.

21
Living quarters were often configured as apartment suites, with an antechamber leading to a bedchamber, cabinet or boudoir, and dressing room. Often the rooms will be arranged in a series, with their doors exactly aligned.

22
About half the rooms in a grand house should be bedchambers for visiting guests. That means a 100 room house may have 50 bedchambers, most of which lie unused much of the time.

23
Stone walls must always be thicker below than they are above. Assume the walls of a grand house are 2′ to 5′ thick. The walls of a residential castle (such as a 16th century tower house) are usually 5′ thick. The walls of medieval castles are anywhere from 5′ to 15′ thick. Remember to account for the thickness of walls when creating a detailed floor-plan. Also, thick walls create opportunities for you to run secret passages within them!

24
Eighteenth century rooms tend to be relatively sparsely furnished, and the furniture was usually pushed to the sides of the room to leave the center empty. The cluttered effect common in the later Victorian age was considered undesirable.

25
There would not be any large windows on the first floor of a fortified house or castle. Conversely, the windows of a stately home or chateau built in safer times and places would often be larger than those in more modern structures. Windows will have shutters – either exterior, or else interior ones that fold into the thick wall on either side of the window.

26
Very large grand houses often had interior courtyards. It was not unknown, however, for there to be completely enclosed rooms without any exterior walls at all. Such rooms would often have a window to admit light from an adjacent room that has an actual window to the outside.

27
Many grand houses will have been occupied by the same family for centuries, and might have been enlarged and remodeled several times. Thus, the same house could have features of several different architectural styles. A rococo house might stand amid the walls of a medieval castle!

28
The enclosure around the parkland gardens wasn’t just for privacy and security, but could also protect the plants from cold winds. Therefore the walls of British and Northern European estates would tend to be higher than those in France, or in the Mediterranean region.