Complex sentence: The restoration lasted twenty five years and included a taller and more ornate reconstruction of the flèche (a type of spire), as well as the addition of the chimeras on the "Galerie des Chimères".
Split into simpler sentences: The restoration lasted twenty five years and included a taller and more ornate reconstruction of the flèche (a type of spire). As well as the addition of the chimeras on the "Galerie des Chimères".