Did the bells sound more or less like bells, but then again sound electronic, or like a recording? They may not have been bells at all, but electronic samples played through a loudspeaker.
There are too many brands and mechanisms to list here, but most amplify an electronic bell-like sound. They can be simple one-line melodies that mimic clock chimes or musical arrangements with four-part harmony. They can fool a lot of people! If you find the tower from which the music is coming from, but the tower just doesn’t look big enough for the multitude of bells you’re hearing…they’re probably not real bells. Of course, visible speakers or an empty belfry are signs that you’re hearing fake bells.