Nikko (日光, Nikko) is a town at the entrance to Nikko National Park, most famous for Toshogu, Japan's most lavishly decorated shrine and the mausoleum of Tokugawa Ieyasu, the founder of the Tokugawa shogunate.
Nikko had been a center of Shinto and Buddhist mountain worship for many centuries before Toshogu was built in the 1600s, and Nikko National Park continues to offer scenic, mountainous landscapes, lakes, waterfalls, hot springs, wild monkeys and hiking trails.
Nikko and the Okunikko area around Lake Chuzenji, in particular, are well known for their beautiful autumn colors (koyo). In the average year the colors start descending from the higher elevations of Yumoto Onsen in early October, are best around Lake Chuzenji and the Irohazaka road in mid to late October and reach the town of Nikko in the first half of November.
Nikko is located along Japan's Romantic Road.
information source: japan-guide.com