Noon in Ankh-Morpork took some time, since twelve o'clock was established by consensus. Generally, the first bell to start was the one in the Teachers’ Guild, in response to the universal prayers of its members. Then the water clock on the Temple of Small Gods would trigger the big bronze gong. The black bell in the Temple of Fate struck once, unexpectedly, but by then the silver pedal-driven carillon in the Fools’ Guild would be tinkling, the gongs, bells and chimes of all the Guilds and temples would be in full swing, and it was impossible to tell them apart, except for the tongueless and magical octiron bell of Old Tom in the Unseen University clock tower, whose twelve measured silences temporarily overruled the din.
And finally, several strokes behind all the others, was the bell of the Assassins’ Guild, which was always last.
Terry Pratchett, Men at Arms.