Once they were at the cutting edge of engineering, design and construction. Now they are echoes from history. Crumbling and on the brink of destruction, they can be reminders of terror, war and the devastating power of nature, but also of extraordinary events, great innovation and human endeavour.
The series explores how and why they were built, considers the financial and social costs of their failure and examines the environmental and ecological impacts. The series also explores how experts came up with plans to make something beautiful or useful from the ruins.