Common development issues in historic city centers are dense urban blocks (with buildings that do not follow modern construction standards), narrow traffic corridors, and low mobility of pedestrians and cyclists. Modern solutions, like smart traffic control systems, parking restrictions, the introduction of speed limitations and dynamic yellow lanes, increasing control of existing yellow lanes, and the establishment of multimodal solutions, are introduced to eliminate traffic problems in these areas. When it comes to the abovementioned development issues, the historic Lower Town area in Croatia’s capital Zagreb, with residential and commercial buildings and infrastructure dating from the beginning of the 20th century, is no exception. Following a very strong earthquake that hit in March 2020, severely damaging the structures in Zagreb’s historical center, a program for the complete reconstruction of this area is being developed, which will contain the Urban mobility development program. This paper presents the process and the results of Zagreb City’s Lower Town urban transport reprogramming performed by the University of Zagreb, Faculty of Civil Engineering. The main premise of the Zagreb historic center reconstruction program is that the quality of life in the area will be improved through the regeneration of neglected and unorganized city blocks, as well as the planning and construction of new public spaces. The aspiration is the transformation of Lower Town into the "15-minute city". The prerequisite for this is (1) improved mobility and (2) reshaped transportation system, with the emphasis on cost-effective technical solutions and the integration of zero-emission modes of transport, and green mobility. At the same time, it will be necessary to preserve buildings and infrastructure that are part of the identity of the City and to prevent the transformation of the reconstruction process into a process of gentrification.