As you may recall, the St. John's Regional Medical Center in Joplin, Mo., proved no match for an EF5 tornado that struck it in May 2011. When confronted by 200 mph winds, scores of the hospital's windows shattered. Portions of upper floors and exterior walls also were destroyed. Five patients died when flying debris disabled exposed generators, causing ventilators to stop. Others patients died later from injuries sustained during the tornado.

Now Joplin is rebuilding. The newly christened Mercy Hospital Joplin is rising on a new site. The facility's two generators will be housed in a reinforced bunker. Fuel tanks for the generators will be located below grade.

Two of Mercy's nine floors also will be located below grade, where 14 operating rooms will be shielded by concrete walls. While those floors also will serve as evacuation points, points further aloft will be designed as safe zones and sealed by heavy metal doors.

Elsewhere, a 12-ft-by-12-ft below-grade tunnel will route power lines from utility plant to hospital. The utility plant will be encased in a hardened exterior.

Of all St. John's windows, only laminated units enclosing a psychiatric ward managed to withstand the tornado's winds. Similar to auto safety glass, laminated units will enclose all of Mercy Hospital.

Windows and frames for Mercy's emergency center will be impact tested to ensure they can withstand hurricane-level winds.

These are the hard-won lessons of Joplin. Who could have imagined an EF5 tornado 40 years ago, when St. John's was constructed? Not its designers and builders.

Now they know. And so do we.