By 1450 he composed a great mappa mundi - a world map - with surprising accuracy, including extensive written comments reflecting the geographic knowledge of his time.
1450. aastaks koostas ta tohutu maailmakaardi (nn mappa mundi), mis oli üllatavalt täpne ja millele oli kirjutatud ulatuslikke tema aja geograafiateadmisi peegeldavaid kommentaare.