One-Million-Liter Test Sphere, Biological warfare test facility in Frederick, Maryland, US
The One-Million-Liter Test Sphere is a massive steel structure standing four stories tall with a diameter of about 40 feet (12 meters). Its walls feature multiple access ports positioned around the circumference for handling specimens inside the chamber.
The sphere was built in the early 1950s as a research facility for biological experiments at Fort Detrick. After research operations ended in the late 1960s, it survived a significant fire in the early 1970s.
The facility became known for hosting hundreds of military volunteers who participated in medical studies. The site represents a period when scientific research pushed the boundaries of both safety and ethics.
The sphere is located on the Fort Detrick grounds and is not open to the general public. Access requires special permission and is typically limited to guided tours during specific events or occasions.
The structure was one of the largest aerobiology chambers ever constructed, capable of holding up to one million liters of air. Its name comes from this impressive capacity, which made it unique for research at the time.
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