As you approach the front of the sign, go to the far right and look for a small, black canister about 10 inches above the ground. Plenty of parking is nearby, although you will need to take a short walk to retrieve it.
Beware of the high muggle activity during the day and evening. You may need to be extra stealthy to get this cache without being caught. Please replace it as you found it.
Congratulations to SwitalaINC for FTF!!!