Developments of legal, institutional and technical aspects in realizing property registration of 3D parcels situated above and below 2D parcels are still evolving in many countries. 3D cadastres have to deal with various institutional/legal gaps and challenging information integration regarding the Rights-Restrictions-Responsibilities (3R) of 2D parcels. This paper aims to present a proof of concept implementing 3D cadastre of a new regulation of land registration in Indonesia (Government Regulation Number 18/2021 on Rights to Manage, Land Rights, Strata Title and Land Registration). This study presents the modelling and validation of 3D cadastral objects for realizing the first registration using the new regulation on 3D cadastre. The study encompasses 2D & 3D data integration, 3D modelling, field validation and visualization of 3D units. The 2D parcels were extracted from the land registration map, collected from the Central Jakarta and the South Jakarta land offices. The 3D constructions to be registered were obtained from PT. MRT in the form of as-built drawings of floor plans and selected cross-sections. The 3D models were created by reconstructing 2D floor plans and cross-sections using Autodesk Revit to create an IFC file of 3D units from geometries of floors, walls and ceilings. Surveyors validated 3D representations of 3D units of two MRT terminals. Field validation includes determining the legal spaces against the 3D constructions and validating floor areas and volumes of 3D units. After field validation is done and agreed upon by stakeholders, 3D models were converted into CityGML to create representations of legal spaces of 3D units. The tools used to convert IFC into CityGML 2.0 are Sketchup City Editor and eveBIM. Data conversion results must be cleaned and edited to include the semantic of 3D units and registration attributes. The results of the integration of 2D and 3D parcels are presented in Terria Map, which shows the constructions, legal spaces of 3D units and 2D parcels with rights.