Which city has hosted the most events?
SELECT T1.city FROM city AS T1 JOIN hosting_city AS T2 ON T1.city_id  =  T2.host_city GROUP BY T2.host_city ORDER BY count(*) DESC LIMIT 1
SELECT T1.city FROM city AS T1 JOIN hosting_city AS T2 ON T1.city_id  =  T2.host_city GROUP BY T2.host_city ORDER BY count(*) DESC LIMIT 1
[{'City': 'Nanjing ( Jiangsu )'}]