The oldest are south-west of the city, at Fort Zeelandia, a modest, fading ghost of the now-vanished Dutch empire. Standing next to Fab 18 produces a strange emotional whiplash. If AI eventually destroys us all, then Fab 18 will be the place it started. And this is why sweet, sunny Tainan is the world’s most dangerous city. Fab 18 is likely built above sites of ancient, ritualised murder.