Think of the UK and you'll probably think of London. Picture France and you'll no doubt conjure up images of Paris and its iconic Eiffel Tower. To many, capital cities define a country. They're often the seat of power, the economic and political hub and sometimes the home to royalty - along with millions of city dwellers. For a place with so much influence, it's important to get its location right.

Sometimes we have to look into history to find the reasons why a capital city ended up where it did. The site of what is now London was by the river: easy to settle, easy for trading and easy to defend. However, it's not located in the country's centre and there's often criticism from far-flung corners of the nation that they are forgotten by the decision makers in the capital. Other countries have taken a different approach by establishing their capitals in the geographical centre so they can exert control and project unity, like Madrid in Spain for example.

Occasionally, there have been reasons to relocate a capital. St Petersburg, founded by Peter the Great in 1703, was Russia's capital from 1712-1918, before the government changed it to Moscow. This was partly because Moscow was more central, and the government decided it was less likely to be invaded by another country.  

And now in Indonesia there are plans to move its capital, Jakarta. Its new location is yet to be decided, but the reason for the move is that this megacity is sinking at one of the fastest rates in the world. It's been built on very swampy land and isn't helped by lots of groundwater being extracted to use for drinking water and washing. The city is overcrowded too and roads are often gridlocked.

Of course, if you can't move your capital city, why not construct a brand new one? Brazil moved its capital from coastal, crowded Rio de Janeiro to inland Brasilia in 1961 - the idea being to build a brand new capital "to bring progress to the interior of Brazil", as architect Oscar Niemeyer described it. And more recently, Nay Pyi Taw was built in 2005 as Myanmar's new capital. This remote city is four times the size of London and has huge roads, golf courses and a zoo – but few people.