What did our cities' natural landscapes originally look like? In a sprawling metropolis such as Tokyo, with concrete encrusting almost every inch of earth, walling every riverbank and towering up to the skies, it is almost impossible to imagine.

Thankfully, the Institute for Nature Study in the heart of the capital maintains a fragment of an old ecosystem to aid the imagination in this regard. There, just a short walk from Meguro Station, this 200,000-sq.-meter patch of forest and wetland remains very much unlike a typical urban park.

Take a few steps inside on a winter's day and, after following a path cutting through thick bush, the city's endless swaths of skyscraper simply disappear. In their place a feeling of being immersed in a vital, breathing wilderness takes over, replete with lush evergreens, ponds, fallen trunks, marshes, exposed roots, insects, eerie bird calls, mysterious rustles behind veils of criss-crossing branches and dark earth carpeted in a mosaic of fallen leaves. In fact, the habitats here are so well preserved that the institute has served as an ecological research site for more than 60 years.