This archive contains approxmiately 1500 VMF source files for several cut maps created by Valve during Half-Life 2s development.

You can compile any of these VMF files using Valve's Hammer Editor, (both the current retail version and the one that is in the Beta's 'bin' folder) allowing you to play these maps in-game, either using the Retail build of the game or the "Beta" build.

Same mappack, but with maps sorted for easier navigation
How to configure beta Hammer
How to fix maps from this mappack