Outside of the States the worst pizza I ever had was in Athens. However, none of us had had any in nearly a year so we scarfed it up and returned to the restaurant day after day. Ever since I have been partial to onion pizza- which is all they served.
The BEST was in Stockholm. It might have been the finest I've ever had. How those Swedes managed to make such a fabulous pizza is beyond me. But they did.
I also had the best lasagna in Copenhagen. It looked and was served exactly like the lasagna in Northern Italy- which was pretty darn good. Better than American casserole style.