Saudi Arabia is trying to build the largest linear city ever. It's a visionary but flawed concept, urban planners say.

• Saudi Arabia has embarked on its ambitious project to build a city in the shape of a line. 
• While the concept of linear urban design has existed since the 19th century, few have attempted it. 
• Business Insider asked architects, urban planners, and academics  whether a line is a good shape for a city. 

Saudi Arabia is constructing a huge mirrored city in the desert.

The Line, as it has been named, is actually a megacity consisting of two skyscrapers that was originally intended to stretch out for 170km, with the aim to eventually house nine million people.