'The Dragon Throne' is a term used in English to refer to the Grand Chair of State in Beijing's Forbidden City (the former Imperial palace). It's also used in a figurative sense to refer to the Chinese imperial state and the monarchy itself – in much the same way as 'the Chrysanthemum Throne' refers to the monarchy of Japan.
The term refers to the dragon symbol which is depicted on the imperial flag and other imperial objects, including Emperor's clothes and the throne itself.
I can find no reference to an Altar of the Sun, as such, in Beijing. There is a Temple of the Sun, which (like all temples) has an altar, but I can find no examples of the name 'Altar of the Sun' being used explicitly for that altar.
The Altar of the Sunne is a location in Pokémon (referred to in Japanese by a name that simply means 'Altar of the Sun').
© Macclesfield Quiz League 2017