Arbitrary construction is defined as any construction or installation, which is carried out or has been carried out without the required building permit or in excess of it or in violation of the applicable urban planning provisions or based on a permit that has been revoked or cancelled. Accordingly, arbitrary change of use is defined as any change of use for which the required building permit (building permit) has not been issued. It is possible, on a case-by-case basis, to either subject unauthorized constructions and uses to the provisions of Law 4495/2017 or issue a legalization permit.