in 1837; north is roughly to the right At the beginning of the 19th century, Brussels was still in many ways a
medieval city. The
Royal Quarter in the historic upper town, inhabited mainly by the
nobility and the richer members of the
bourgeoisie, was upscale and modern. The rest of the city, however, in particular the lower town, located in the western half of the
Pentagon, in the valley of the
Senne river, was densely populated and industrial, characterised by an illogical street layout, back alleys, narrow streets, and numerous dead-ends. The Senne split into two branches in
Anderlecht, penetrating the Pentagon, the former site of the
second city walls, in two places. The main and more southern arm entered through the Greater Sluice Gate, near today's
Brussels-South railway station. The smaller northerly arm entered through the Lesser Sluice Gate, near today's
Ninove Gate. The courses of the two traced a meandering path through the city centre, forming several islands, the largest of which was known as
Saint-Géry Island. The two branches met up on the north side of Saint-Géry Island, exiting the Pentagon one block east of the Antwerp Gate. A man-made arm, called the "Lesser Senne" (, ), continued on the borders of the Pentagon in the former
moat, outside the
sluice gates. It followed the
Brussels–Charleroi Canal before rejoining the main part of the Senne north of the city. Still described, in the 18th century, as a river with a "useful and pleasant course", the Senne had long since lost its usefulness as a
navigable waterway, having been replaced by the first half of the 19th century by the Brussels–Charleroi Canal and the
Brussels–Scheldt Maritime Canal (also known as the Willebroek Canal). The Senne had always been a river with an inconsistent flow, often overflowing its banks. In times of heavy rainfall, even the sluice gates were unable to regulate the flow of the river, which was often swollen by numerous creeks flowing down from higher ground. Making matters worse, within the city, the river's bed was narrowed by encroaching construction due to demographic pressure. The supports of numerous unregulated bridges impeded water flow and caused water levels to rise even further, exacerbated by a riverbed of accumulated waste. During dry periods, however, much of the Senne's water was diverted for the needs of the city's populace, as well as to maintain the water level in the Charleroi Canal. This left a flow too feeble to evacuate the filthy water, leaving the
sewage, garbage,
detritus and industrial waste that had been dumped into the river to accumulate in the stagnant water. The Senne, which a witness in 1853 described as "the most nauseous little river in the world", had become an open-air
sewer spreading pestilential odours throughout the city. Early in the second half of the 19th century, Brussels saw numerous dry periods, floods and a
cholera epidemic, caused as much by the river itself as by the poverty and the lack of
hygiene and
potable water in the lower city. This forced the governments of the
Province of Brabant and the
City of Brussels to act. ==Attempts at purification==