No, this isn't a secret UFO installation. It's a natural underground gas tank that contains over a billion cubic meters of helium, important in many industrial processes, located under America's Great Plains. It's covered in mines, domes, and pipelines.
This area outside Amarillo, TX, called Cliffside Field, is a natural mega-tank for helium: The ground beneath the fields contains massive caverns that are airtight. From Mammoth, we get geological (and poetic) explanation:
This industrial landscape is only possible due to the particular geologic conditions of the region: beds composed primarily of "Brown dolomite" are sufficiently receptive to helium (having been discovered because they contained natural - though less concentrated - helium reserves), while the "Panhandle lime formation", which is layered immediately on top of those beds, provides a natural "caprock", penetrated only by the airtight injection wells (PDF). With those wells, production plants, maintenance roads, and pipelines running across the surface of these formations to prosthetically adapt bedrock to use in industrial process, the ground itself has assumed a hybridized and mechanical nature, comprising a very literal landscape machine.
Basically companies shoot helium into these giant caverns, and then install "wells" that act as nozzles that can be opened to let the gas out.
According to a recent article in Seed:
Helium's "Fort Knox" is the Federal Helium Reserve (FHR) near Amarillo, created in 1925 to supply a fleet of military dirigibles that never fully materialized. During the Cold War, when helium was crucial for military and civilian space programs, the FHR linked up to a larger network of gas fields, pipelines, and refineries, growing to contain roughly a billion cubic meters of helium and accruing a $1.4 billion debt in the process. Though the FHR still holds more helium than any other stockpile by far, its stores are rapidly diminishing.
With so many industries depending on helium, these Texas gas bubbles are as valuable as oil fields.