"Game of Thrones" fans can officially mark their calendars: The series' highly anticipated prequel "House of the Dragon" will debut on Aug. 21, HBO announced Wednesday.

"House of the Dragon" takes place 200 years before the events of "Game of Thrones," a medieval fantasy series that became a global phenomenon during its eight-season run.

The new 10-episode series will be based on George R.R. Martin’s book "Fire & Blood" and will tell the story of House Targaryen, HBO said.

The network announced "House of the Dragon" at an event in 2019 to stir enthusiasm for the HBO Max streaming service. The drama also will be available on HBO television.

The series stars Paddy Considine as King Viserys Targaryen, a warm and kind man chosen by the lords of Westeros to succeed the Old King, Jaehaerys Targaryen, and Matt Smith as Prince Daemon Targaryen, younger brother to King Viserys and heir to the throne.