Nanjing's geography makes it not only one of China's great ancient capitals, but also helps accommodate a modern-day local green movement.
The city was never large in terms of area, due in part to the defining City Wall, but it does have natural features: mountains to the east; the Xuanwu Lake in the centre; and the Yangtze River to the west.
The city is still in the early stages of its green development, so much of the eco-tourism options available require initiative and effort to see.
Home-style hotels, temple grounds and parks along the foot of Stone Mountain or south of the city centre along the banks of the Yangtze River are accessible by bicycle via small country roads and pathways. No tourist company yet offers such tours of the old capital's green and historic sites, but that shouldn't stop any determined traveller from exploring.
The best place to start is on top of the City Wall, which encloses the city centre and skirts the edge of Xuanwu Lake. Nanjing's city walls are ironically the first stop for the green-minded visitor.
A bike ride along, or on top of, the walls will lead you through the Confucius Temple District, past the lake to Zhonghua Gate, facing east towards the Purple Mountains.