Complex sentence: No less than 47% of the medieval section of the city was completely lost, and along with the 1795 fire, it is the main reason that few traces of the old town can be found in the modern city.
Split into simpler sentences: No less than 47% of the medieval section of the city was completely lost. Along with the 1795 fire, it is the main reason that few traces of the old town can be found in the modern city.