Around 83 percent of NASA’s facilities are beyond their design lifetimes, and the agency has a $3.3 billion backlog in maintenance. When you consider NASA’s $250 million estimate for normal year-to-year maintenance, it would take a $600 million uptick in NASA’s annual budget for infrastructure repairs to catch up on the backlog within the next 10 years.

“Worst” in terms of being overdue for repairs, not that they don’t produce great work.