This chapter focuses on Local Digital Twins (LDT) as a data driven decision support system that allows public administrations to connect data from different policy fields using various technologies to strengthen data driven and evidence-informed decision-making. The specific value of an LDT lies in its connection between different systems and related data to support policy-making. Eight meta-requirements (MR) policymakers have towards LDTs and how they can connect to nine LDT meta-features (MF) are presented based on five years of LDT research experience and several research projects. The theoretical features and requirements are substantiated with practical examples of three research projects: the digital twin of Bruges (Belgium) and the Horizon Europe-funded PRECINCT and URBANAGE projects. The different MF demonstrate that an LDT is a system-of-systems (SoS), with functionality residing in the overall system resulting from interactions between several operationally and managerially independent systems. Each system covers specific domains or topics, contributing to the overall purpose of an LDT, addressing cross-domain systems and issues, fostering cross-domain simulations and cross-department and organisation cooperation.