The solution to the first twelve puzzles will be the name of a capital city. It can be the capital of a country, state, province or major administrative division.
If you would like to post your solution, please mention the day in your reply, and place the city name between [spoiler] and [/spoiler] tags.
For example (this is not the first real puzzle), suppose I post
The only city that has hosted the Summer Olympic Games three times.
[spoiler]London[/spoiler]