Historian and writer Dan Cruickshank celebrates architecture as a creative force as he explores the world's greatest cities, buildings and monuments. Since building began, architects have tried to build the future, create fantasy worlds, and even change humanity through new inventions. Dan travels to Yemen to reveal an ancient city of skyscrapers made of mud and explores the Eastern State Penitentiary in Philadelphia, where society dreamt of reforming criminals into decent men.

• Dan Cruickshank

• Dan Cruickshank