Comparing Helsinki in 1809 to 2007 shows the extent of land reclamation over time. Still continues. Waterfront harbor area is new, and there is an ongoing project in Kruunuvuorenranta. The US is a bit of an international outlier in doing zero new land reclamation

As in the US, private businesses in Helsinki built both the housing and transit connections, benefiting from private value capture

You can compare 1850 to 1980 here. A lot of land particularly in the Southwest harbor area was reclaimed. As the goods harbor gets moved to Vuosaari, this opens up a lot of space in the city for development