The Complete Systematic Land Registration (PTSL) activity is a Government program to achieve legal certainty and the existence of a single map in Indonesia. Therefore, the target of PTSL is land that does not have a certificate in one village. Prior to the PTSL activity, there was an activity called the National Agrarian Operation Project (PRONA). These activities were not successful, so there was a new land registration system called PTSL. The methods used in this research are normative and empirical juridical methods. The results of a study on the implementation of Complete Systematic Land Registration (PTSL) in Indonesia show that it has provided legal certainty to land owners. However, in implementing PTSL in Indonesia, there are still obstacles in the implementation of PTSL. These obstacles include the lack of adequate human resources to support the implementation of PTSL, the lack of facilities and infrastructure for implementing PTSL in the regions, the lack of full support from the community for PTSL activities, and the large tax costs on land owned by the community.

The provision of land to build green open spaces in urban areas as in the city of Yogyakarta is important considering that the increasing activities of urban communities will cause various environmental problems, such as an increase in vehicle smoke pollution, a decrease in the quality and quantity of groundwater, flooding, and so on. This study aims to determine how the implementation of land acquisition for the construction of public green open space in Yogyakarta City and the obstacles that arise in land acquisition for the construction of public green open space. This research is a type of empirical juridical research, which begins with understanding the legal rules or norms governing green open spaces in urban areas. Because of the limited land available to build this Public Urban Green Space, what the Yogyakarta City Government does is one of the ways to acquire land to build Public Urban Green Space is to buy people's land as allowed in the Land Acquisition Law and its implementing regulations.