This talk investigates the role of diagrams and maps in late medieval mnemonic practice and devotional reading. It centers on a previously unknown plan of Jerusalem in Prague, National Library, MS XIV A 8, and a nearly identical map in Erfurt, University Library, MS CA 2° 108. Both accompany Peter of Poitiers’ Compendium historiae in genealogia Christi (late 12th century). We argue that these maps functioned as cognitive and devotional instruments for structuring, visualizing, and memorizing sacred history.