Complex sentence: Nibby excavated in the area of the Forum Romanum from 1827, and cleared the Cloaca Maxima in 1829 and was an expert in the topography of Rome and its hinterland.
Split into simpler sentences: Nibby excavated in the area of the Forum Romanum from 1827, and cleared the Cloaca Maxima in 1829. He was an expert in the topography of Rome and its hinterland.