What is this thing? (huge muffler outside an industrial building?)

Does anybody know what this thing is? It looks like a huge vehicle muffler. The building appears to be leased to Verizon, but that could be the suite next door, it’s unclear.

There is another unit just like it a few yards down. I would assume that they were auxiliary HVAC units, but they don’t appear to be attached to the building, just next to it in the parking lot.

Any ideas?

My guess is that it is a muffler sitting on top of a backup generator.

What Dewey said.

Yep. The gray box the rusty muffler is sitting on contains a diesel engine & generator. The louvers on the end correspond to the front grill on a car. There’s a big intake fan & coolant radiator right behind those louvers.

Bog standard istallation at nearly any big building. If you have computers or elevators you need a generator like that. Likewise most buildings big enough to have central fire alarms. That stuff needs power any time the building is occupied.

Thanks, all!