Bartolomeo Ammanati's three lovely elliptical arches follow drawings by Michelangelo.
The elliptical arches created by Bartolomeo Ammanati were made in the 1600s. 
mnli hypothesis: The elliptical arches created by Bartolomeo Ammanati were made in the 1600s.  premise: Bartolomeo Ammanati's three lovely elliptical arches follow drawings by Michelangelo.