Most are rural roads, but a small number have also been built in cities such as Chennai and Mumbai.
In the '90s, the government built fences in border cities such as San Diego, California, and El Paso, Texas, which forced immigrants to make more perilous journeys through the mountains and desert.
In the early 21st century, increased traffic congestion and the need to revive downtown areas led to increased interest in the streetcar, with new systems being built in some American cities, such as Houston, Texas Tampa, Florida and Washingtonon, D.C.
Someone who would bring with them the billions of pounds of investment needed to ensure we don't just build city baubles such as the new Library of Birmingham or New Street Station but rather grow more cleverly connected places that extend out of the Big City Plan and into the most deprived areas of our region.
All the Palestinians in Syria are caught up in this new disaster because their camps after 1948 were usually built on the outskirts of cities such as Damascus and Aleppo.
Alexander the Great left behind artisans who built Greek-styled statues at cities such as Alexandria Oxiana, now Ai Khanum, on the Oxus River.
In cities such as Las Vegas and Farmington Hills, Michigan, sensors built into streetlights allow them to brighten or dim and monitor air quality.
Cities such as London have built this infrastructure over centuries, but those expanding now have to do so in much less time, and often with little money: more than 90% of urbanisation between now and 2050 will take place in low and middle-income countries, according to the World Health Organisation.
In some instances, entire cities, such as Los Angeles, have been built on alluvial fans.
