BELLINI: Madonna and Child with Saints (San Zaccaria Altarpiece) 1505, oi on wood transferred to canvas, 16'5" x 7'9", San Zaccaria, Venice. The oil paints used were very slow drying, typically 'sun bleached stand oil' was used. This partially polymarized vehicle, that is clear and sticky like honey, will not fully dry in ten thousand years! This keeps the paint film constantly flexible. This probably accounts for the excellent state of preservation. LINK to a Smarthistory video to learn more.
Bellini's - Madonna Enthroned with Child and Saints
Leonardo's vitruvian man (@ Accademia)