Unearthing the secrets of a grassy mound at Nashville's airport

We got a question about a grass-covered mound — or building? — at the corner of Thompson Lane and Vultee Boulevard, near Nashville's airport and the iconic gold box of a building known as International Plaza.Educator and sixth-generation Nashvillian Sonia Fernandez LeBlanc is a big Curious Nashville fan — such a fan that she knew we had slowed down on answering questions in the last few years. But she said to herself that if we ever revived the project, she was asking about this mysterious mound she just began to notice.I know it's probably mundane, but they are working hard to make it just blend in with nature and yet there are stairs, air ducts and drainage pipe in the stone wall.I have driven this route for decades and just noticed that it was something more than a hill in the past seven or eight years. I can't be alone in wondering!WPLN's Blake Farmer met her out there and invited a Metro agency to pinpoint the answer.