The aim of the article is to find and substantiate an efficient use of unoccupied land plots in the central districts of Saint Petersburg. Three sectors of the city center were investigated and the most appropriate type of functional building assignment was chosen for the land. For this purpose in the research there was an analysis of the location of the chosen sectors, the experience of using the land of demolished buildings, the real estate market of the districts on which the land plots are located, also there was an interview of citizens for evaluating the potential exploitation of the sectors on certain criteria. According to the results, an art-development center got maximum rating but because of the economic reason – little space payback, building of the center is beside the purpose. The second place was given to a sports center but as one is currently situated not far from the investigated territories building of this structure is unprofitable. The third rating was for an overground parking which is very essential in the center of the city. As the social and economic significance of the parking are very high this object is the most favorable for building on the unoccupied territory. Efficient use of the land plot by choosing this object to be built in the central part of Saint Petersburg is confirmed by analyzed factors and results of the interview.