Here's a fact that should haunt every powerful person on earth: the greatest empire of the ancient world didn't fall to a siege. It fell during a party. On the night of October 12, 539 BCE, Babylon — the most fortified city anyone had ever built, with walls so thick chariots could race on top of them — was conquered while its rulers were getting drunk. The Persian army was camped outside the gates. And inside? They were pouring wine.

The place
Babylon
The Writing on the Wall
MENE, MENE, TEKEL, UPHARSIN — the night a mysterious hand wrote an empire's death sentence on a palace wall
Moral of the Story
“Empires don't announce their end. They throw feasts. They drink from golden cups. They count their walls and tell themselves that what's stood for centuries can't fall in a single night. But history keeps its own score, and every kingdom gets weighed in the balance — mene, tekel, upharsin — numbered, weighed, divided. The writing is always on the wall. The question is whether anyone's sober enough to read it.”
Characters
Source
Daniel 5 (biblical account of Belshazzar's feast); The Nabonidus Chronicle (BM 35382, British Museum); The Cyrus Cylinder (BM 90920, British Museum); Herodotus, Histories I.191 (fall of Babylon); Xenophon, Cyropaedia VII.5 (festival and river diversion); The Verse Account of Nabonidus (BM 38299); Beaulieu, Paul-Alain. The Reign of Nabonidus, King of Babylon 556-539 B.C., Yale University Press, 1989; Kuhrt, Amélie. 'The Cyrus Cylinder and Achaemenid Imperial Policy,' Journal for the Study of the Old Testament 25, 1983; Collins, John J. Daniel: A Commentary on the Book of Daniel, Fortress Press, 1993