One of the earliest known sewers was the Cloaca Maxima in Rome, built (c.6th cent. B.C.) to drain the site of the Forum. Although London's drainage system dates from the 13th cent., the discharge of offensive waste into it was illegal until 1815. The Parisian sewers were constructed before the 16th cent., but by 1893 fewer than 5% of the city's houses were connected to the system. As early as 1701, Boston had drains. Generally, however, systematic sewage disposal was not widely introduced until the mid-19th cent.