tower block

A tower block, high-rise, apartment tower, residential tower, apartment block, block of flats, or office tower is a tall building or structure used as a residential and/or office building. In some areas it may be referred to as an "MDU", standing for "Multi Dwelling Unit". In the United States, such a structure is referred to as an apartment building or office building, while a group of such buildings is called an apartment complex or office complex.