This is just an old demo map from the game. Its not in the main game but play it if you want I guess.
How to download:
Extract the file
Drag and drop the .bsp file to your maps folder
C:\\Steam\steamapps\common\Half-Life 2\hl2\maps
Then open up half-life 2
Open up the console by pressing "`"
If it does not work go to options / advanced / enable developer console
When you are in the console type in "map citizenstories"
bang