Construction is a tier three technology that unlocks the Windmill and the Destroy ability. The Windmill is a building that produces one population for every friendly adjacent Farm. The Destroy ability removes a building or Ruin at no cost but also removes any population or points provided by the building.
Cymanti has the Recycling technology instead of Construction. Recycling unlocks the Decompose ability, which is identical to the Destroy ability except that the Decompose ability removes the building or ruin at the end of the turn (instead of immediately) and returns a building's full cost.