A smart city or ville du futur is an urban environment boasting high living conditions not only today, but for future generations too. It is a city founded on principles of sustainable development. Accessible energy resources and sustainable consumption is widely accepted as a key requisite for urban development, with energy efficient technologies as integral components. Cities cover a mere 2% of the earths surface, but account for 75% of energy consumption and 80% of CO2 emissions. The Trianon Dialogue, a Russian-French civil society forum initiated by the presidents of the two countries, has put forward several topics for discussion. These include questions concerning the development, construction, management and modernization of cities; and implementing digital technologies in the urban infrastructure, thereby developing the theme of the dialogue for 2018: «City of the Future». Experience has enabled French and Russian cities and energy companies to cite numerous successful examples in urban planning, automation, building security, electrical fixtures, and housing management systems, and all in environments where the urban population is growing apace, and where citizens expectations are high. What needs to be done for a city to become smarter? How can energy efficiency be increased, and how can fast-developing digital technologies be integrated in the urban infrastructure? What results in optimizing electricity consumption and minimizing energy losses have Russian and French cities achieved? How can the environment be protected as urban spaces grow and new projects are implemented?