While most of lower Man­hattan was without power, one key building remained lighted: 60 Hudson Street, one of the most important Internet hubs worldwide. Even during the worst of the storm, the building kept the country connected through an array of well-maintained generators.

If you’ve ever sent an email, your data has probably trav­eled through a fiber-optic cable here. Built around 1929, the building served as the hub for Western Union’s telegraph network and is now known as one of the fastest connections between world financial centers; it maintains Internet connectivity for en­tire regions of the country.

Property manager Shaun Mooney, former Marine and volunteer firefighter, describes this job as “Mis­sion Critical”—“the lights have to stay on no matter what.” Preparation for Sandy started the week before the storm, with staff meetings devoted to assessing supplies and personnel needs. When power in lower Manhattan went out on Monday eve­ning, chief engineer Ernesto Martinez’s team monitored generators and pressure sen­sors. To make sure windows didn’t blow out, his team opened select airway chan­nels throughout the building to equalize pressure.

The group slept in cots and sleeping bags “in just about every uncomfortable place we could,” Martinez said with a laugh. “It decreases sleep time,” he added. He arrived Sunday and didn’t leave until Wednesday evening.

During the crisis, one of the building’s main concerns was fuel. With much of the Northeast dealing with fuel shortages, 60 Hudson turned to the Department of Homeland Security for help making sure they never ran out. The key to keeping a building as important as this one up and running, Mooney says, is breaking down the job into small components you can focus on. “And all of a sudden you have a major impact,” he said.