I took the test at FTE Jerez since they were the only center that tested up to level 6 (iirc), and ahead of time they gave me a document of what to expect. There were no surprises. First part consisted of them asking me some basic questions about myself. Then there was a section where I looked at a photo and described it, a section where I watched a video and described it, and another one where I had to read something and talk about it, and finally a section where I listened to simulated ATC recordings and had to identify incorrect read backs. Took about an hour or so and was easier than I thought it was going to be. After about three days they came back with my ICAO level 6 report and sent me a certificate in the mail.