Complex sentence: At the end of 1809 he went to Rome, where he remained until 1812; he also travelled, to Naples, the Sabine Hills, the Alban Hills, and the Campagna.
Split into simpler sentences: At the end of 1809 he went to Rome, where he remained until 1812. He also travelled, making trips to Naples, the Sabine Hills, the Alban Hills, and the Campagna.