I haven’t read all of the references mentioned there, but could point you to some of the resources:
It says:
Quintilian makes it clear that non-alphabetic signs can be employed as memory images, and even goes on to mention how ‘shorthand’ signs ( notae ) can be used to signify things that would otherwise be impossible to capture in the form of a definite image (he gives “conjunctions” as an example).
It cites Quintilian, Institutio oratoria, XI, ii, which can be found here:
It also says:
This makes it clear that though the architectural mnemonic with its buildings, niches and three-dimensional images was a major theme of the art as practiced in classical times, it often employed signs or notae and sometimes even non-physical imagined spaces. During the period of migration of barbarian tribes and the transformation of the Roman empire the architectural mnemonic fell into disuse. However the use of tables, charts and signs appears to have continued and developed independently.
I’ve only started De Umbris Idearum, but that might be the source of the information about Giordano Bruno’s system of signs. You might want to check out these discussions:
Mary Carruthers has made it clear that a trained memory occupied a central place in late antique and medieval pedagogy, and has documented some of the ways in which the development of medieval memorial arts was intimately intertwined with the emergence of the book as we understand it today. Examples of the development of the potential inherent in the graphical mnemonic include the lists and combinatory wheels of the Majorcan Ramon Llull. The Art of Signs (Latin Ars Notoria ) is also very likely a development of the graphical mnemonic.
I’ve only read part of Mary Carruthers’ The Medieval Craft of Memory, but that has some examples of memory spaces that aren’t necessarily palaces, like the Guidonian Hand. See also: Miniature memory palaces - including your palm and Medieval art as mnemonic. Lynne Kelley’s book, The Memory Code, is also a great source of ideas.
If you have a more specific question about it, let me know and I’ll see if I can find an answer. 