If it's as big as you say, it's likely a bald-face hornets nest and those suckers pack a wallop if they sting you. They are very territorial and will chase you down if you go near the nest.
As much as I hate to say it, they are actually good bees because they prey on those nasty yellowjackets and other unwanted garden bugs....
I hate yellowjackets. Had one sting me 3 times as it fell down the front of my shirt...once on the neck, then on my stomach and finally on the top of my foot before I got to stomp on it....they are nasty..did a little yellowjacket dance to get it out of my clothing...screamed also...
I wonder if those in the hive killed all the yellowjackets...if so they deserve to live a few more weeks...I even had yellowjackets make a good size nursery in a old bird feeder I hadn't used in a while...just about filled up the feeder.