Workers begin grinding the marble chunk-infused floor of the Media Lab extension’s central atrium, which will be polished to a glossy finish. The expanse of interconnected airspaces surrounding the atrium necessitated smoke curtains (left) for emergency air evacuation, shown here closed for testing.

Sam Range—The Tech

Workers begin grinding the marble chunk-infused floor of the Media Lab extension’s central atrium, which will be polished to a glossy finish. The expanse of interconnected airspaces surrounding the atrium necessitated smoke curtains (left) for emergency air evacuation, shown here closed for testing. Sam Range—The Tech