The term "Memory Islands" was inspired by the ancient "Art of Memory" which described how people in the antiquity and the Middle Ages used spatialization to increase their memory capacity. The method of "loci" (plural of Latin locus for place or location) consists of creating a virtual map and associating each entity to designated areas on the map. In this paper, we propose a new method in the field of automated cartography based on the notion of Memory Islands for hierarchical knowledge. We first describe our novel method for cartographic visualization of knowledge (e.g. ontology and its skeleton which is taxonomy), we then show how the technique of "Memory Island" helps to navigate through information contents to memorize their locations and to retrieve them. We also discuss the design principles of this approach. Finally, we present an experimental prototype that is intended to evaluate the psychological relevancy of Memory Islands. We present also some preliminary empirical results showing that the use of Memory Island provides advantages for non-experienced users tackling realistic browsing and visualization tasks.