Generally, a World Expo lasts six months. But planning for it can take around a decade. And the impact it makes on a city can last for centuries.  How do cities carry the memory of such an enormous event? In the first of a two-part series on Expo legacies, we’re bringing you two stories about two very different Expo experiences, one in London and one in Lisbon. They take place more than a century apart, but at their core is Expo’s tradition of harnessing big ambitions. This podcast is by Expo 2020 Dubai and produced by Kerning Cultures Network.