The World Cities Culture Forum doesn't include stats on a few other cities known for their wealth of museums.
If you want to add to your bucket list, you should start with Mexico City. The cultural hub is home to the Museo Nacional de Antropología, one of the finest archaeological museums on the planet, as well as museums focused on the works of national favorites like Frida Kahlo and Diego Rivera.
In the U.S., Washington, DC's museums are notably all free, and provide an exemplary education on American history, air travel, spycraft, the Holocaust and so much more.
History buffs will marvel at the institutions in Athens, Greece, where ancient Greek artifacts abound at the National Archaeological Museum, and you can also step back in time at the Byzantine and Christian Museum and Museum of the Ancient Agora.
And then, of course, there's Rome, where museums devoted to history, art and even cuisine (there's a museum dedicated to pasta!) meet; Beijing, which hosts museums both traditional (the Beijing Museum of Natural History) and not (the Tank Museum; the Bee Museum of China); and Barcelona, where you absolutely can't miss CosmoCaixa, one of Europe's most extensive, spectacular science museums.
The world is, in short, full of cities touting a fantastic array of museums. You can't possibly fit them all in over your lifetime. But you'd be wise to see as many as you can.