Nine Altars and Eight Temples
The Nine Altars and Eight Temples refer to 17 sites in Beijing that played a significant roles in imperial ritual and worship under the Qing dynasty, some of them going back to earlier periods of the history of Beijing. As some of the altars are clustered in the same locations, the same ritual venues are occasionally referred to as only "Five Altars and Eight Temples".
Source: Wikipedia — Nine Altars and Eight Temples (CC BY-SA 4.0)