When the missiles were falling on Haifa during the 2006 Second Lebanon War with Hezbollah, Israelis scurried down to bomb shelters. But not everyone was able to make it down to safety; the elderly, the infirm, and especially those hospitalized in northern Israel had no choice but to hunker down and pray that Hezbollah’s missiles missed them.

To prevent such a scenario from recurring, Rambam Medical Center in Haifa spent over $100 million and eight years constructing the world’s biggest fortified hospital. This week, it conducted a drill simulating what it would be like to move hundreds of patients from entire units — including the intensive care units — downstairs into the Sammy Ofer Fortified Underground Emergency Hospital.

Normally used as a parking lot, the vehicles that usually park in the underground facility were banned for the day, and the usually hidden equipment, beds, sinks, and other hospital features were opened (they are stored in closets in the walls of the lot). Built into the walls and floors of the facility are all the power outlets, connections, air conditioners and heaters, water and filtration systems, and anything else needed to move hospital operations underground.

In anticipation of a wartime emergency, conversion of the facility — from parking lot to hospital — can take less than 48 hours, hospital officials said. In case of a war, air vents and entrances would be closed within the bottom two floors, while independent air, electricity and water supplies would allow the underground hospital to be entirely sealed off from the outside world for up to 72 hours, if necessary. The hospital has its own generators and secure water supply.

Construction of the facility was a major technical and engineering challenge, hospital officials said. The facility is so deep underground that its lowest portion extends beneath the water table, which required the pumping of millions of liters of water. When construction actually began in late 2010, the first stage was the pouring of 7,000 cubic meters of concrete to form the base of the facility — basically using all the concrete available in northern and central Israel at the time, with no other concrete available for other projects for days before or after.

The facility was dedicated to the memory of Sammy Ofer, the self-made Israeli multimillionaire who passed away in 2011, and donated nearly $20 million to build the facility.

The drill allowed hospital staff to practice the transfer of patients (played by young army volunteers), and equipment to designated locations on each of the floors of the underground hospital. That equipment included complex dialysis and surgical equipment to reassemble operating rooms and intensive care units. In a real war situation, the hospital said, staff would be assisted in moving everyone and everything underground by the Home Front Command, the Health Ministry, Magen David Adom, and the Haifa Municipality.