 A drawing by Michelangelo indicates that his early intentions were towards an ovoid dome, rather than a hemispherical one.In an engraving in Galasso Alghisi' treatise (1563), the dome may be represented as ovoid, but the perspective is ambiguous.Stefan du Pérac's engraving (1569) shows a hemispherical dome, but this was perhaps an inaccuracy of the engraver.