The Large Hadron Collider uses a technology called WorldFIP to synchronize systems within 10 nanoseconds. WorldFIP is a fieldbus, a technology used to network a large number of systems together -- something the LHC obviously needs. Like the timing systems used to coordinate neutrino tracking between CERN and the LNGS, WorldFIP is linked to a GPS system. The data from that system is relayed to equipment across the Large Hadron Collider to keep everything synced to universal time.
With an oscillator-based master clock, CERN can supply its equipment with time data with an accuracy of one nanosecond. One of the WorldFIP system's most challenging tasks is keeping 1,800 power converters synchronized to within one millisecond. It also serves to synchronize radiation monitoring, magnet positioning, cryogenics and other systems at the LHC.
Of course, not every system at the Large Hadron Collider has to be accurate to such a degree. Some have wiggle room of tens or even hundreds of milliseconds. Considering the installation is so huge and packed with some of the most complex technology in the world, that's still pretty impressive.