 Complete the following phrase:  During the 19th century, the population of Brussels grew considerably; from about 80,000 to more than 625,000 people for the city and its surroundings. The Senne had become a serious health hazard, and from 1867 to 1871, under the tenure of the citys then-mayor, Jules Anspach, its entire course through the urban area was completely covered over. This allowed urban renewal and the construction of modern buildings of hausmannien style along central boulevards, characteristic of downtown Brussels today. Buildings such as the Brussels Stock Exchange 1873, the Palace of Justice 1883 and Saint Marys Royal Church 1885 date from this period. This development continued throughout the reign of King Leopold II. The 