The significance of American expos in the history of world’s fairs, as well as in the history of planning, urban design, architecture and landscape architecture is extraordinary. In the article, which constitutes the first part of a report on the carrying out of the research project entitled “Urban and architectural heritage, as well as the impact of American world expos on city planning and development”, a retrospective outlook on American world expos has been presented on the examples of New York and Chicago, with a particular focus on their long-term heritage, which affects the development of their host cities.

This paper presents the issue of the vertical extension of buildings, mainly residential, as an element of sustainable housing policy of European cities. This type of construction project allows for the acquisition of additional residential space, using the existing technical infrastructure, and also not deepening the effect of urban sprawl. Vertical extensions allow for the construction of new apartments in urban areas, being one of the forms of densifying the existing buildings. The study reviews research on the subject of vertical building extensions, trying to answer the research questions posed: how and with the use of which building analysis tools it is possible to improve the process of vertical extension, so that it can become an actual element of the housing policy of cities. Three original studies were selected for the analysis: from Germany, Belgium and England, which met the criteria set by this study, presenting a universal scheme of action for vertical extensions, not treating them as incidental, individual construction intervention, and treating vertical extensions as an element of systemic action for the acquisition of new apartments. The selected studies are carried out in countries economically and culturally similar to Poland, which was also one of the selection criteria. The study is also to be a voice in the discussion on the possibility of the vertical extension of residential buildings as an element of housing policy in Poland.

The significance of American expos in the history of world’s fairs, as well as in the history of planning, urban design, architecture and landscape architecture, is extraordinary. In the article, which constitutes a supplement to the first part of a report on the carrying out of the research project entitled “Urban and architectural heritage, as well as the impact of American world expos on city planning and development”, a retrospective outlook on American fairs has been presented on the examples of Philadelphia, Buffalo, Saint Louis and Cleveland, with a particular focus on traces of expos left in the cityscape and their long-term heritage, which affects the development of host-cities.