Need advice on SEO friendly URLs

[eluser]zuluanshee[/eluser]
I'm building a travel site. People will access cities through a tree of sorts. I want to create urls that say
mytravelsite.com/Europe/France/Paris
mytravelsite.com/Europe/Italy/Rome
mytravelsite.com/Asia/China/Beijing

I'm doing this in part because I want to implement breadcrumbs.

My question: is mod_rewrite the only way to do this? There will be a lot of cities. In fact, I've found a list of every city in the world and plan on building a database

I'm afraid i know so little about mod_rewrite, I don't know if this can even be done easily. Does every single city have to be mapped in .htaccess? My city list has about 250,000 cities in it. Or, is there a 'built-in' way to do this with CI?

thanks