During the eighteenth century, Kluuvi bay was turning into marshland, and preventing the city from expanding. Bourgeois citizens insisted that the bay be drained. Other voices pointed to the bay's strategic value offering protection to the city as a natural ditch.
     At the turn of the nineteenth century, J. A. Ehrenström drafted a city plan in accordance with which a drained Kluuvi would become a park and Töölö Bay and the City Bay were to be connected by a canal. The canal project was abandoned when it turned out to be too expensive, but Kluuvi was still to become a park. The southern and eastern parts of Kluuvi Bay were designated as plots for building. In 1833 Emperor Nicholas I set up a committee to

oversee the draining of the bay. The funds were raised by auctioning off the plots in the area, some of which at that time were little more than water and bottomless marshland.
     The bay was dammed and behind the dam a pool with stone edges was built, as a collection point for the water. The water was pumped from the pool into Töölö Bay by wind power. Many loads of sand were driven by horses and poured into the muddy Kluuvi, where solid ground was not to be found until a depth of 20-30 metres. Little by little the streets and blocks took shape. Kluuvi became a residential area for handicraft workers and bourgeois citizens.