This thesis refers to the design approach of a new mixed-use building on a plot of land unused for many years in the center of the city of Larissa. The building being analyzed is located on a plot of land with a total area of ​​2069 sq.m, in O.T. 811A on Asklepiou & Epirou streets. It is a five-level building, which includes shops, office spaces, residences and a basement with parking and warehouses. The general shape of the plot and the requirements for the realization of a complex architectural program with a variety of uses, were basic elements on which the solution of the building was based. Given the need to separate the different functions housed in the building, we were led to a building that develops its functions in height and two staircases that ensure independent entrance to the office and residential areas. The study focuses on the spatial conditions created by the mixed-use buildings, as well as on the modern living needs of the urban space.