Valaam Island on Lake Ladoga is the site of the Orthodox Valaam Monastery. Since the eighteenth and nineteenth centuries, monks have introduced trees and plants not endemic to such northerly latitudes, such as maple, linden, and oak trees, and pear, apple, and cherry orchards, as well as watermelon fields. In 1810, the monks laid out the first major garden to cultivate herbs such as rose hips, valerian, juniper, and mint. Due to the creation of alleys and gardens carefully cultivated by the monks, many of the new plants acclimatized successfully. As a result, Valaam's largely man-made environment is today considered to be one of the most dense and diverse biospheres in Europe.