The Great Saint Martin Church was part of a Benedictine monastery. It was in this monastery that the great Flemish cartographer Johannes Ruysch worked. He produced the famous Ruysch map (but not here). The Ruysch Map was produced in 1507. The Ruysch Map displayed the recent remarkable new discoveries of the world, such as New Foundland, Haiti and Cuba. He also noted the presence of codfish in the area of the Grand Banks.
Ruysch probably entered in 1505 the Benedictine monastery of St. Martin in Cologne as a secular priest. He left the monastery quickly and traveled to many places. Some believe he even joined John Cabot in his discovery of New Foundland. He returned to the St. Martin monastery, suffering from consumption, but able to create a, now lost, astronomical wall painting illustrating the days, months (phases of the Moon), and constellations. He is said to have died at considerable age in 1533 at the monastery, where he had a room adjacent to the library.