Complex sentence: The first lazaret was founded by Venice in 1403, on a small island adjoining the city; in 1467 Genoa followed the example of Venice; and in 1476 the old leper hospital of Marseille was converted into a plague hospital.
Split into simpler sentences: The first lazaret was founded by Venice in 1403, on a small island adjoining the city. In 1467, Genoa followed the example of Venice, and in 1476 the old leper hospital of Marseille was converted into a plague hospital.