Planning cities is critical challenge in 21st century

Urban planning has failed to keep up with mass urbanization around the world, placing cities at the epicenter of the 21st century's most pressing challenges, a top United Nations official said on Monday.

The vulnerability of urban habitats, amid the accelerating pace of climate change and population growth, points to an unsustainable future if urgent action is not taken, Peter Thomson, president of the UN General Assembly, said in Quito, Ecuador at the UN Habitat III conference.