The question of the types of objects of unauthorized construction is of great importance for the arbitration process. The main purpose of the study is to correctly determine the object of the claim in cases of recognizing the building as unauthorized, which is the guarantee of a legal and well-grounded court decision. To achieve this goal, the views of scientists regarding the composition of real estate objects, which can be recognized as unauthorized buildings, have been studied. The current legislation, the legal positions of the Supreme Court of the Russian Federation and the Supreme Arbitration Court, expressed by it before its liquidation, and the practice of arbitration courts of the Russian Federation are analyzed. Research results: the concept of a building is disclosed, which is important for determining the object of the claim. Recognition of construction as real estate allowed real estate to be classified into traditional and non-traditional. Traditional objects that, under certain conditions, can be recognized as unauthorized constructions include buildings, structures, other structures, including objects of unfinished construction, non-traditional real estate objects that appeared as a result of the development of certain sectors of the economy, in particular linear objects, apartment buildings, artificial land plots, parking spaces, etc. Since all objects in respect of which claims for unauthorized construction can be filed relate to real estate, a proposal was made to amend Article 130 of the Civil Code of the Russian Federation, adding to the list of real estate objects, those types that are contained in part 7 of Art. 1 of the Registration Law 2015.