Historically, the tallest buildings to be built in New York were office towers. Their height is one of the defining characteristics of Manhattan’s development, and the city’s skyline, filled with towering buildings, is recognisable all over the world. In the twenty-first century, this skyline is also formed by residential towers. We analysed the situation and evolution of housing buildings on Manhattan, buildings that are often built in place of former office buildings. Based on our research, we have observed the existence of two trajectories in the design of twenty-first-century housing in New York. The first is the functional trend and it is based on an increasing hybridisation of function. The second is the trend of height, which is closely linked with developing technological potential, and which often adversely affects access to insolation on lower storeys and to cross-ventilation. We analysed selected cases of buildings and discussed the relationships between these two architectural currents and their impact on the image and composition of the city.