First:
This amazing channel, they do houses tours, basically a free ride:
Second:
Use your body as a memory palace: use your sense of touch and proprioception, it’d could be easy to use any part of your body, also, you can look at other people you know or famous people and use their bodies as well. It’ll obviously be easier with your own body, but it is possible to use other people. In my body I have 90 spots, being conservative.
Third:
Regarding imaginary places, I think they are the most memorable, I think Thomas de Aquinas recommended the use of those. I have places from 2017, I recall what I memorized. I recall the empty images (characters, rooms, mental experiments). I have a room where a bunch of animals are sit on a table, I was supposed to use them to memorize the russian equivalent oftheir names, but I didn’t knew all the concepts of imagery to actually make the translation, so I didn’t use them. And other places and experiments loom in that place.
When creating them, I advised you to don’t go from zero, take a reference, that way is faster and you decide from the beginning how they’ll be. Also, fantastic landscapes, fantastics buildings, like buildings connected through stairs in the air and cableways. Imagine characters, you can use them as loci, and also the character bring life to your paracosm.