## 1 Introduction  
In the City Logistics Research Group of the Department of Material Handling and Logistics Systems at the Budapest University of Technology and Economics [1], we have focused on the logistics systems of the so-called urban concentrated sets of delivery locations (abbreviated as CSDL) since 2015. After data collection, development of several models, and complex analysis, we started a project to examine how to use cargo bikes in the new, innovative city logistics systems of shopping malls--one of the most critical CSDLs--and the first studies have shown that it is worth focusing on this area. In the introduction, the definition of the CSDLs, the purpose of the research, and the structure of the paper can be seen. In the approach of the City Logistics Research Group, the urban delivery locations have two main groups. There are single delivery locations and concentrated sets of delivery locations (urban zones or buildings with a high density of delivery locations), which are groups of single delivery locations with different concentration degrees [2]. Based on our previous research results [3], there are two main types of concentration: concentration with either open or closed infrastructure. In the case of open concentration, the set is marked by an open area, so the stores are surrounded by roads and squares, such as in the case of a shopping or pedestrian area surrounded by urban roads or an open market surrounded by a square. Within a closed infrastructure, the CSDL is marked by a building that makes a set from the single delivery locations. These main groups of concentrated sets of delivery locations have several types (subgroups), as can be seen in Figure 1. It can be concluded that this classification and the characterization of the properties of the typical delivery locations are also significant results of this research. This classification can be important for city logistics system planning nowadays and in the smart cities of the future as well; as for the deliveries of the CSDLs different solutions are needed than in the case of the single delivery locations. As the first step of this research project, a complex data collection methodology was developed [4], which helped to collect data about 5 CSDLs from Budapest (4 shopping malls and 1 shopping area) and 540 stores within them. In Budapest, there are 32 shopping malls with a sum of 3432 stores. In the data collection phase, 4 of these 32 shopping malls were examined, with a sum of 663 stores (19% of all the stores from shopping malls in Budapest), and 377 of them answered our questionnaire (57% of the examined stores and 11% of all the stores of shopping malls in Budapest). Additionally, we examined the most significant shopping area of the city (the \"Vaci utca\" shopping area), with 418 stores. In this research, 163 of them answered our questionnaire (39% of the stores of the shopping area). The collected data provided input for the modeling, where a complex mathematical model [3], a mesoscopic simulation model for the examination of the physical parameters and the cost structure [5], and a topological model for shopping areas [3] were developed. Based on the results provided by the simulation, the consolidation-based, multi-stage city logistics solutions can result in significant savings in the examined systems, both in terms of performance indicators and costs. The field understudy is significantly important because in every former research, only some sub-systems of the systems were examined, and not with the analysis, simulation, and optimization of the whole systems with several different types of CSDLs. Much research examined the consolidation centers, the cross docks, and the technological solutions, and some projects focused on some well-defined types of CSDLs. In one project, the optimal position of shopping malls and logistics centers were examined based on performance and cost parameters [6], and in another one, the loading and parking areas of a shopping mall were in focus [7].