This paper describes the use of 3D real property formation at a major construction site in Stockholm, Sweden, project Slussen. Real property formation with complex 3D volumes and numerous real properties and associated rights, restrictions and responsibilities (RRRs) has to be shown with the real properties and RRRs in relation to each other. The present legal solutions and documentation thereof are based on analogue documentation (digitalised to pdf) and cannot be attached as e.g. dwg files. Architects and other professionals do not normally have access to the 3D real property boundaries in their 3D building models from the beginning of a project and the exact locations of boundaries are agreed upon during the formation process to achieve as usable solutions as possible. The aim of this paper is to describe the 3D property formation process when involving complex solutions securing RRRs to solve legal and planning challenges on different levels of detail. The paper focuses on the cadastral real property formation procedures using 3D property formation for constructions above and underground, as well as how they are registered in the national real property register. The paper illustrates a complex 3D property solution and adds to the understanding of the challenges of registration and visualisation of Swedish 3D real property in Stockholm, focusing on legal as well as technical experiences. This research is a document study based on an analysis of the property formation and planning documentation and processes of a cadastral procedure conducted in the Slussen project, as well as associated documentation from other agencies, and by interviewing key persons involved in the project. The paper illustrates the need for a national cadastral index map in three dimensions to be used in the formal real property formation procedures, to achieve a comprehensible and correct representation and visualisation of 3D real properties and RRRs in Sweden. The results can be used as input in coming property formations of a similar kind, as well as a component for the development of a national three-dimensional cadastral index map. Furthermore, the results can be an input to capacity building for the future use of 3D models as part of the formal cadastral property formation procedure.