poor suburbs to access Medellín’s city center and its amenities. D- Actors and governance Here and elsewhere, infrastructure can restore social ties among different urban communities City-level authorities are in charge of leading urban transformation so that it embraces sustainable development. Infrastructure has ramifications in every realm of human life. It However, because they may lack the expertise and skills enables cities to prosper and grow. It is key to their sustainability required to do so, most of them call on the private sector via and to people’s well-being. Given that infrastructure is what public procurement, tenders, and collaboration. Public-private makes cities possible, it follows that great infrastructure makes partnerships are a key organizational form of collaboration, great cities possible, and sustainable infrastructure makes because in many cases the private company takes charge of sustainable cities possible. However, it cannot be taken for both the building and operational phases of a project. granted that great infrastructure will continue to be a defining trait of great places. What will be tomorrow’s Great Wall of Three prerequisites are required to successfully bring about China, Golden Gate Bridge, or Eiffel Tower? Continuing to be sustainable urban transformation: proper urban planning, “citizens of somewhere” means that locations will still be integration of the interests of diverse stakeholders, and a sustainable and livable, and they will possibly made so by new focus on sustainable building materials and practices. Suitable infrastructure. The Great Green Wall in Africa is an example in urban planning is grounded in long-term visions. Identifying this regard.55 stakeholders requires new mechanisms and processes to be set up. In addition to voting, forms of direct local democracy, Finally, the development of sustainable infrastructure will local referendums, and neighborhood inhabitants’ initiatives require a combination of: are all experimental tools for stimulating discussion and •Sustained support and participation at governmental level; negotiation with all public, private, and civil stakeholders. It is •A commitment to public and private investment; crucial to recognize that a large spectrum of stakeholders is •A legal and regulatory framework. affected by the design and implementation of policy programs. City executives should aim to offer relevant solutions based This combination of support, commitment, and framework on initial discussions, efficient deliberating processes, and should help to deliver initiatives that live up to expectations. synergy-based ecosystems that include all stakeholders. Successfully including citizens and communities as key players in projects is a key factor in creating social acceptance of It is essential for cities to define governance frameworks them. It is crucial for policy makers to be aware of the place that integrate all stakeholders in urban transformation, from that needs to be given to citizen participation. Citizens are citizens and external organizations to the different management unquestionably stakeholders when it comes to achieving urban layers (those which tackle, for example, strategic, tactical, and transformation, governing social norms, regulating economic operational considerations) of the local government. Doing so activities, and implementing new environmental standards, all should result in more efficient governance. of which serve as the bedrock of sustainability. Finally, frameworks should be structured in such a way Public funding will be important, but private sector investment that priorities can be defined, processes can be managed, needs to be scaled up. A clear city government policy is required achievement of different objectives and allocation of resources to identify public infrastructure priorities. Well-defined urban can be monitored, and everyone’s perspectives and actions can planning must support sustainability considerations. Many be included. Establishing a regime of clear governance will also financial mechanisms can assist city governments in investing result in better coordination among and between the different in sustainable urban transformation: fiscal incentives for internal players (for example, the municipality’s departments) investors, industry regulation, sustainability standards, new and external players involved. low-carbon technology, and better data analysis. The overall framework will rely on capacity-building mechanisms, stakeholder activism, and forms of innovative financing (for example, social bonds) that supplement and complement private financing efforts. (55) The Great Green Wall is an African-led movement that started in Senegal and has the ambitious aim of building an eight thousand-kilometer natural wall across the entire width of Africa, from the west coast to the east coast. https://www.greatgreenwall.org/about-great-green-wall (accessed on 5 July 2021). 45 Quélin and Smadja | HEC PARIS | SMART CITIES | The sustainable program of six leading cities | 2021