Gandor was an ancient city on Mars, inhabited by the eponymous Gandoran species.
By the time the Second Doctor, Jamie and Zoe visited Gandor, it was the last city on Mars, previously home to many other civilisations, and was ruled by Zaadur.
The Gandorans created the Ice Warriors, originally a slave species that later became the dominant Martian civilisation. (AUDIO: Lords of the Red Planet)