We meet Yuai Mtumwa, who employs a team of women plasterers in Zanzibar to restore Stone Town’s crumbling architecture; academic Dag Nilsen, student Kjell Jacobsen and museum director Hans Pederson, who campaigned to save Norway’s longest terrace of wooden buildings; and a trio of Chinese heroes – Zheng Liqun, Huang Yung Sung and Ji Ping – who prevented the 2,400-year-old Cichen town from being swallowed up.