Thanks for the guesses!  #21 is The Hague, Netherlands.

#22 – For this one, you either know it or you don’t.

This is the world’s smallest independent state, both in area and population (821 people).  It is landlocked with a wall separating it from the neighboring country.  It is ruled by a non-hereditary, elected monarchy.  The state has no diplomatic service of its own and embassies to this state are located in another country’s capital city.  The state has a non-commercial economy.