Normandie '44 was my first released multiplayer Half-Life level. I created it in 1999; one of its intentions was to apply for a professional game graphic designer - and I'm happy it worked :-) (together with some other samples)
The major advantage of this level is its relatively good graphics - measured to the old Half-Life engine and the low requirements. Another advantage is that there are many hideouts - I love Duke levels ;-)

The major disadvantage is that it's simply too big - one of the most common beginner mistakes.

Normandie '44 (Zip file)
Please look into the readme for install notes.