Reclaimed land.
Yes, in some cases you can build on reclaimed land. This will vary depending on which type of land is being reclaimed. Land that housed a garbage dump is often reclaimed for woodlands rather than for homes.
in the Netherlands we call reclaimed land "polders"
polder
cambodia
Yes
Examples: Parts of Tuas are on reclaimed land. Jurong Island used to be two separate islands. The land between the islands was reclaimed to fuse them together.
Lands reclaimed by the sea can be called either land fills or reclamation ground. In New Zealand, it is called land rehabilitation.
It is Kansai Airport.
The Netherlands is particularly known for reclaiming territory from the sea, so that would be your answer. Some other countries have also reclaimed land to a lesser extent.
Land that is reclaimed by diking and draining is called a Polder
ondergelopen grond