Answer: Adverse Possession
Explanation:
Adverse possession is considered as the legal principle in which a person tends to attain legal ownership of particular land or property without actually getting permit from legal owner along having legal title .This claim is based upon continuous usage of that land for occupation or other purposes.
According to the question,transfer of property right from legal owner of that land to the person who is possess it long period of time in a build. He can appeal court to get legal title with his name and after that property will belong to him legally.