[Endoperez]

When you start the game, you have one province, in which you have a lab, a temple, a fortress, and some nation-spesific sites. This is your capital.

All nations have a capital. Most often the name of the capital is the same as the name of the nation, so e.g. C'tis (the nation of lizardmen) started from a province named C'tis, which has C'tis national sites (Temple Marsh, Empoisoner's Guild), a fortress and a lab. The C'tissian temple was destroyed when you conquered the province, and in theory, a random event might have destroyed the lab. You still get lots of gold from there, get a "free" castle, and quite often decent income of gems you wouldn't have otherwise.

The AI defends its capital very heavy-handedly, and conquering and holding enemy capital often means that you're winning the war. Even in multiplayer games, there are only few exceptions, which usually include ridiculous strategies that are fun to play but won't (usually) win the game. Gandalf Parker, as an example, has played Pangaea by conquering few "dots" here and there (stealthy forces), then building a fort, a lab and a temple with a stealthy Dryad, and advancing to conquer many small "nations" which his enemies eventually would conquer - only to be very surprised to not have found his capital, or a route to his other provinces.