Horace Dediu's presentation on the history of Amsterdam features the amazing land reclamation map above. Utrecht, which is now inland, used to be a port. And Amsterdam is where the ocean used to be. Haarlem is part of the mainland but looks to be located on what was once a barrier island.
It's a commonplace of economics that they're not making any more land, but this is a powerful reminder that once upon a time it was actually pretty common for technologically advanced societies to build more land. Leaving that era behind us is probably a good idea (imagine the environmental impact review!), but that only makes it all the more important to try to use the land we do have wisely.