We’ve looked at many of the world’s largest things in the past, so for something different, let’s look at the longest. Karl-Marx-Hof in Vienna is the world’s longest residential building, stretching more than a kilometre through the 19th district better known for large houses and diplomatic residences. The building consists of almost 1,400 apartments, meant to house up to 5,000 people. The design included amenities such as a swimming pool, library, laundries, shops, a school and medical facilities. Only the eastern side of the building stretches the full 1,100 metres, but in many sections there are blocks on the western side of the development which create internal courtyards and parks for the residents. The building consists of almost 1,400 apartments, meant to house up to 5,000 people. The design included amenities such as a swimming pool, library, laundries, shops, a school and medical facilities. Only the eastern side of the building stretches the full 1,100 metres, but in many sections there are blocks on the western side of the development which create internal courtyards and parks for the residents.