The US Army built a surge hospital for Los Angeles coronavirus patients in just 3 days during the weekend of March 28. The hospital was built on top of the convention center parking garage. It was built so fast and surreptitiously that even some local police officers in the city don't know it exists. This hospital was in addition to the conversion of the Los Angeles Convention Center into a military field hospital for coronavirus patients. The army started both sites [the parking garage rooftop hospital and LA convention center conversion] on Friday night and was finished by Monday morning.