The world is urbanising at a breath-taking pace – The World Bank estimates that around 180,000 people move into cities every day. Against this background, London is something of a veteran. One of the oldest ‘world cities’, many of its streets, public places and buildings – and some of its institutions – date back centuries.

Yet the city remains extraordinarily vital. Only 20 years ago, in 1994, the historian Roy Porter introduced his best-selling London: a social history by predicting that the capital's days as a pioneering, global city were coming to an end. How wrong he was. London's economy has boomed over the last two decades. Although the city was deeply implicated in the banking crisis that began in 2007, it has weathered the ensuing economic storm better than the rest of the United Kingdom – more cranes have been erected in London over the last three years than across the remainder of the country as a whole. The city has attracted a large number of migrants from all over the world, including poor people and billionaires, and absorbed them seemingly successfully. Much to everyone's surprise, the 2010 Census revealed that Londoners describing themselves as ‘White-British’ are now in a minority, yet a large majority of residents say that people of different backgrounds in their local area get on well together.

There are many things that anyone transported from the London of 1994 to the London of 2014 would find surprising. But several in particular would likely stand out. First, the time-traveller would be impressed by the level of investment in transport infrastructure, after decades when the Underground, in particular, had remained neglected. Second, he or she would surely be surprised by the creation of a popular new pan-London government, centred on the very un‑British novelty of a mayor – only one in 20 Londoners support the abolition of the mayoralty. The 2012 Olympics showed what was to many people around the world – and to many people at home – an unfamiliar city, apparently safe (or at least safer than it was), efficient, democratic, creative and confident in its diversity. The capital's universities, and cultural institutions – the Tate Galleries, National Theatre, Globe, the British Museum, to name a few – are enjoying relatively good times and have an increasingly international reach.