Complex sentence: Van der Geest was a big fan of Matsys and owned several of his paintings, including this one, while also commemorating his hundredth death anniversay with a new plaque in the Antwerp Cathedral.
Split into simpler sentences: Van der Geest was a big fan of Matsys and owned several of his paintings, including this one. He also commemorated Matsys' hundredth death anniversary with a new plaque in the Antwerp Cathedral.