Trams are coming back to the streets in most of the world’s cities. This is a real revolution in transport systems. A trend that has led to the implementation of new tramway systems in a lot of cities in all five continents, including the great capitals. Their reintroduction comes in response to the new paradigms of sustainable mobility which are appearing, both in policies for the recovery of urban spaces in more central parts and in the structuring of metropolitan areas on the basis of high capacity forms of transport. User acceptance of the tramway has been very high and it often becomes the means of transport most highly valued. The new tramways, together with the prioritization of pedestrian areas, the growing use of bicycles and the promotion of the other forms of public transport, exemplify the social will to achieve a sustainable model of mobility for the cities of the 21st century.