This is an excellent, highly recommended, harrowing film about the ordeal of a boy in war. If you liked it "Come and See" is another Russian film on the same theme.
There are many fine European films about the war. "Das Boot" is one of the most remarkable. The same director made a film about Stalingrad, called "Stalingrad." It gives more information than "Enemy at the Gates," but doesn't have the drama. Between the two films, you can get a better idea of what was going on in Stalingrad.
Andrzej Wajda's "Kanal" is about the Warsaw rising, and has some startling scenes. "Closely Watched Trains," a Czech film is another classic. "Europa, Europa" is also worth seeing: the story of a young Jew who survives the war in the Hitler Youth.
The thing about European films about 1939-1945, though, is that there isn't this split between the "war film" and tales of the home front in the period. So you can get a lot of WWII on the screen without seeing any battles or armies. "Hope and Glory" is a fine British film about a boy growing up in the 1940s. Not a war film in the conventional sense, but pervaded with the spirit of the war. It's similar to Spielberg's "Empire of the Sun," more lowkey, but also more real and memorable.
"Fortunes of War" (drama involving WW II)
Another fine choice. A British miniseries about a woman who's husband works for the British Council in the Balkans. The book is better, though, and filled with little details of the time and place that don't come out on the screen.
"Memphis Belle" was also a good view. By now the recent film may come packaged with the documentary that inspired it. And don't forget some of the old British films of the day, like "the Dam Busters."
For something really off the wall, there's the British television series "Goodnight Sweetheart." A 1990s Englishman discovers a passage in London than can take him back to the 1940s. A silly exploitation of nostalgia, but I can't help wondering what he decided to do at the end of the series.