Marathon

And when Heracles was still a boy, but already of extraordinary strength of body, the king strongly desired that his daughters should bear children by him. Consequently he invited Heracles to a sacrifice, and after entertaining him in brilliant fashion he sent his daughters one by one in to him; and Heracles lay with them all, brought them all with child, and so became the father of fifty sons. These son all took the same name after the daughters of Thespius, and when they had arrived at manhood Heracles decided to send them to Sardinia to found a colony, as the oracle had commanded.


- Diodorus Siculus, Library of History, Book 4, Chapter 29, Section 3