As our commentors guessed, this hole that used to be the smokestack of the old firepit / gazebo is now a solar tube skylight. John the builder framed in the hole and added supports on the inside.
John and the roofers added the dome on the top of the old firepit hole.
The insulators made it snug and energy-efficient.
John wrapped it in tongue and groove cedar. And voila! We have natural light in the center of the store building.