The Drawing of the Dark

by Tim Powers

Duffy blinked, impressed by the old man’s speech. “And that’s why the Herzwesten is one of the most important centers, eh?” “Possibly the most important.” Aurelianus peered at the Irishman, as if gauging how much revelation he could take at one sitting. “Being Irish,” he said slowly, “you’ve doubtless heard of Finn Mac Cool.” Duffy nodded. “There actually was such a man,” Aurelianus said. “He was the High King of these people I was speaking of, the nomadic beaker people—call them Celts if you like, it’s not entirely inaccurate—and he died here.” He pointed at the floor. Duffy automatically peeked under the table. “Here?” “He’s actually buried under this building,” Aurelianus told him. “You mentioned the old Roman fort that used to stand here; it was built around this brewing cellar, which had been producing beer for two thousand years when the first Roman saw the place. The brewery was built thirty-five centuries ago, to be a marker over Finn’s grave.”

Here's the basis of a roleplaying campaign!