Complex sentence: After 1823, farms begin to be sub-divided into lots, which were advertised as suitable for a "country retreat" for Manhattanites, leading to a building boom that resulted in Brooklyn Heights becoming the "first commuter suburb," Rizzo, Joanna.
Split into simpler sentences: After 1823, farms begin to sub-divide into lots--advertised as suitable for a "country retreat" for Manhattanites. This created a building boom that made Brooklyn Heights the "first commuter suburb," Rizzo, Joanna.