You can use any phonetic numbering system, for letters and numbers.
There are other systems, but they’re more complex to explain, although the basic principle is the same. You can use a route like “palace,” which is easy since you can create new ones if you want by searching online, with a 3D view.
But I like to bring them to life using literature, comics, movies, etc. You extract characters and place them in a location.
You can name the location and use the initial letter to mark the index. Objects from one location can travel to another to index locations.
You can create 3x3=9 grids, meaning in a room with 6 areas like the 4 walls, 1 floor, and 1 ceiling, placing 3 to 10 images within each square, and within each image, an active character. You can number everything, like room 1 with 162 loci (9 x 6 x 3 = 162). This means room 1 ranges from 1 to 162, although you can also number it from 1 to 100, giving you 1,000 loci with just 10 rooms (this saves a lot of time creating loci). This allows you to place a lot of information in one space. If you want, each room can have a theme, like an airport with objects of that category in that room, and so on.
I separate the visual information into categories, such as visual idea, color idea, movement idea, etc. So, an area could be black, like a charcoal square, a black sword, a raven, smoke, etc.
There are so many ways to create fantastic places, using just about anything. These days, there’s so much easily accessible information online that it’s practically impossible to create massive memory palaces.