reclaimed land; landfill
Refers to land created by filling in a body of water, often for construction or development. The term is also famously part of the place name 築地市場 (Tsukiji Market), which was built on reclaimed land.
This area was originally sea, but it was expanded by land reclamation.
築地市場はその名の通り、埋め立て地に作られた。
Tsukiji Market, as its name suggests, was built on reclaimed land.