Digital Clock dependent on central source

Hi all,

I’m building a digital clock for my school’s website. Our school’s clock system isn’t synchronized to a central system, so we find our individual classroom clocks being inconsistent with one another over time. A typical Internet clock pulls its time from the local computer. Is there a source and/or way to have this information retrieved from a more central, worldly source, whereby the time is taken from a reliable source outside the school?

Thanks for your help!

Jeff