A map of our data centers can be found here: https://www.cloudflare.com/network-map, and they're also listed on https://www.cloudflarestatus.com/, sorted by continent. The three-letter code preceding their name on that list is the IATA code of the nearest major international airport.
To find out which data centre your traffic is currently being routed to please visit the following url http://www.example.com/cdn-cgi/trace replacing example.com with your domain name.
fl=21f63 h=www.cloudflare.com ip=22.214.171.124 ts=1420194924.494 visit_scheme=http uag=Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_1) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/39.0.2171.95 Safari/537.36 colo=LHR spdy=off
The above output is what you would see when you visit the URL, the colo section will correspond with the above table, in this example traffic is being routed to London, GB