Complex sentence: In 1325 Galeazzo I, after a long siege conquering the city, bgegan new great works of defense: the bifurcation of the River Lambro (the branch Lambretto) and the construction of a castle, the third in Monza.
Split into simpler sentences: In 1325 Galeazzo I, after a long siege conquering the city, began building new defenses. Among the projects was the bifurcation of the River Lambro (the branch Lambretto) and the construction of a castle, the third in Monza.