Bologna, Italy

Bologna sits in northern Italy's Emilia-Romagna region with roughly 390,000 residents, and it has anchored learning in Europe since the University of Bologna opened its doors in 1088 as the oldest university in continuous operation worldwide. A UNESCO-listed network of 38 kilometres of porticoes lines the historic centre, sheltering pedestrians beneath the Two Towers raised by rival families: the 97-metre Asinelli completed in 1119 and the 48-metre Garisenda, which now leans 3.2 metres off vertical. The 1779 Teatro Comunale hosted the premiere of Rossini's Barber of Seville, and the city lays claim to both tortellini and ragù alla bolognese. Engineers are still watching one of those medieval towers inch further sideways.