Their seat was the castle of Harrenhal, which was granted to them after the extinction of House Harroway. However, the Strongs also died out, like all the Houses to hold Harrenhal, and the castle was passed on to House Lothston.
In the books
There have been a number of historical Strongs mentioned in the books. One was Ser Lucamore Strong known as "Lucamore the Lusty". He was a knight of the Kingsguard during the reign of Jaehaerys I who broke the Kingsguard vows of chastity by secretly marrying three women and fathering sixteen children. His sworn brothers discovered this and informed the king, who then had the Kingsguard geld Lucamore and sent to the Wall to join the Night's Watch.
Another notable Strongs were Lord Larys Strong, Lord of Harrenhal, who served as Master of Whisperers under King Viserys I and King Aegon II, and Ser Harwin Strong, lover of Rhaenyra Targaryen and rumored father of her first three children.
Houses from the Riverlands