Complex sentence: He started his architectural career in 1561 with the works in the Royal Palace of Aranjuez, following it in 1562 with "Libro del saber de astronomía" ("The Book of Astronomical Knowledge").
Split into simpler sentences: He started his architectural career in 1561 with the works in the Royal Palace of Aranjuez. In 1562 he had written the "Book of the Astronomical knowledge" ("Libro del saber de astronomía").