Fallout 3 Vault Tec Headquarters

w Have you arrived at VaultTec headquarters in Fallout 3? 3

I keep trying to use the card, but to no avail.

VaultTec is headquartered in Vernon Square. However, if you can't get there quickly, head to Chevy Chase East (subway station north of GNR) and walk around the subway until you reach the gate called Vernon Square. Get it Open it, circle it and look for the small location marker on your perception gauge and walk towards it until you reach it.