Mental palaces are open to interpretation. There is no single authority in the world who can say which mental palace is better. Here I will provide some of my own ideas, which are unique to my approach.
Finding mental palace
We use our mental palaces to store all sorts of visualizations. This is one of the oldest and most useful mnemonic devices. In Rome, it was a temple, and in popular culture, it is often depicted as a library, but most people practicing memory arts use simple houses they know intimately well. The most useful palaces are our own homes, homes of our parents and friend, or hotels where we stayed.
Personally I do not remember houses very well but I tend to remember streets and maps, so I utilize very simple artificial buildings similar to what you find in MMORG games. Then I place these buildings in the streets of visualized cities.
Whatever building you start with, you will need to modify it to use effectively. Notice that real places are also often redecorated, moving furniture and painting walls.
Navigating mental palace
The main purpose of redecorating your mental palace is to facilitate your movement within. Typically we follow the same itinerary in a mental palace, doing it at our top speed and not crossing our own path. Most people run or glide through their mental palaces. Personally I fly through my visualization like a body-less spirit not limited by laws of physics.
Now, we do not want to run into doors, chairs and other stuff. So we need to clean up the passageways reducing the number of breaks and turns required. We might need to make a permanent opening in a wall or move some closets to get a faster itinerary.
This redecoration is kind of permanent, as we tend to reuse the same palaces for many different visualizations.
It is most convenient to place objects along the walls and corners. A PAO visualization tends to be a statue of human proportions, and we need to clean up the spaces for those statues. We might move furniture or even throw something away, as we need an unobscured view for our visualizations.
Sometimes we will want to put more complex stuff like mindmaps along the walls. So we need to hang the relevant whiteboard.
These home improvements tend to be permanent. If we expect to see a whiteboard in a certain place, we will put it there in all of our visualizations. So the visualized mental palaces justify our efforts.
Keeping the character of the place
We should keep some details constantly in place to provide context for our visualizations. Each wall and corner should be instantly recognizable. To this end, we use material possessions with a high emotional value and positive associations. Closets, small tables and chairs, beds, electronics, musical instruments. It is possible that if the original building was not sufficiently unique we need to add objects.
We do not want to clutter our mental palaces with too many details that may defocus us. It is best to remove pictures, collections of memorabilia like plates and photos. We need to visualize each part of the mental palace instantly, so we cannot use complex objects.
A library might not be a very good mental palace if we try to remember each book, but if, instead, we remember a texture of brown book covers, the visualization will be fast.
Please notice that my focus here is on speeding up the process. If your goal is simply to remember, you might do fine keeping all the details you want.
How many visualizations per room?
Some people tend to place one visualization per room and wonder why their mental palaces are not big enough. Others put so many visualizations in one room, they forget where to look for them.
We want to have all visualizations of a similar size so that we do not need to zoom in and zoom out between the visualizations. Zooming is defocusing and may cause vertigo. Usually, we observe our visualizations from one or two focal points in the middle of the room: e.g. in a circle or an ellipse. Each time we can chunk in four visualizations. So small rooms will probably have 4 visualizations, while larger rooms can have 8 or 16 visualizations along the walls and corners.
Occasionally we need to add visualizations after the construction of the mental palace, and it is not very uncommon to find some objects out of the regular order. Please try to keep the outliers below 10% of the objects you visualize.
Stairs and utility spaces
We try to have significantly more rooms than stairways and keep the number of stairways to a minimum. Fortunately, this also applies to actual architecture, so if you are using actual houses you should be fine.
I avoid placing visualizations on stairways unless I want to mark an entire floor. Then I can put two huge statues per floor.
Human attention follows certain rules. If you visit your fair share of museums, you will start to understand intuitively what should call for attention and where to put the red tape “for stuff only”.
For example, you might want to remove the utility spaces like toilets from your itineraries. They are not very large to put complex visualizations and not very pleasant to revisit. Large bathrooms might be sufficiently big and associated with good memories, and they also have a lot of character.
We might add dividers to make better use of the space. Classical mental palaces use columns to mark the end of one space and the beginning of another. We might get modern and put plants, fish tanks, low wardrobes or counters.
With dividers, a large room effectively becomes multiple small spaces, and multiple small rooms act as a single chunk. Dividers are not very often used in small palaces, but very instrumental in large spaces.
Walls, floors, and ceilings
We usually try to keep large clean spaces like walls, floors, and ceilings from drawing too much attention. So we use a single color or pattern for them. The specific color changes per visualization, to create a better context for the visualization.
You can stay with the original colors of the original home, typically off-white. This is a clean solution.
As an alternative, you can place elaborate pictures, like they often do in catholic churches. Placing elaborate doors, windows, floors, and ceilings enable encoding of complex and optional pieces: stories within stories.
Sometimes I use the practice of elaborate floors and ceilings for statistics and proofs which are present in scientific works but not absolutely required for comprehension.
Familiar and recognizable
In some articles, I recommend adding special magical features like portals to deal with specific issues. It is recommended to keep this creativity to the necessary minimum.
You may choose to do various modifications of your mental palaces, but the place must be familiar and recognizable. It is recommended not to renovate your mental palaces too often: once a year will work.
The whole idea of a mental palace is reusing a well-known and intimately familiar place and itinerary within the place to hold new stuff. This way we reuse the context and modify the details. If something is out of place it immediately catches our attention.
If the context starts to change too much, we might lose the home base advantage.