Tiantaishan, or Mount Tiantai, lies near the coast (about 40 kilometers inland) in the upper half of Zhejiang Province, roughly halfway between the major cities of Wenzhou to the south and Ningbo to the north (Mount Tiantai lies roughly 100 kilometers south-southwest of Ningbo and roughly 150 kilometers north-northeast of Wenzhou). A third fix on Mount Tiantai puts the mountain about 180 kilometers southeast of the city of Hangzhou, which in turn lies at the western end of Hangzhou Bay.
Mount Tiantai is perhaps best known for its role in Chinese Buddhism: it is the center for the Tiantai School, or tradition, of Buddhism (aka the Tendai School of Buddhism, in Japan), whose most prominent teacher, or spiritual guide, was Zhi-yi (elsewhere written as Chih-che), who came to Mount Tiantai to practice Buddhism in CE 576, during the Northern Dynasties (CE 386-588) Period, but who first made a name for himself as the leader of the Tiantai School of Buddhism - more commonly known as the Lotus Sutra School of Buddhism - during the Sui Dynasty (CE 581-617). However, before Mount Tiantai became a fixture on the Buddhist horizon, it had long been a holy place to Taoists/Daoists.*
Zhi-yi is widely regarded as the first Buddhist teacher who was able to synthesize Buddhist thought, with its many seeming contradictions, into a comprehensive and cohesive system of beliefs (in this sense, Zhi-yi was to Shakyamuni Buddha as the apostle Paul was to Jesus Christ, or as John Richard Hicks was to John Maynard Keynes, the originator of Keynesian economics). It was in large part Zhi-yi's synthesis of Buddhist thought that made Buddhism accessible to the Chinese people (this was only one of two major influences that helped the Chinese people to embrace Buddhism, as the footnote below indicates).
Mount Tiantai is also known as the home of the famous master of the Ch'an School of Buddhism (the Zen School of Buddhism, in Japan), Daoji, or Jigong (Master Ji), as he was also known, though he was more commonly known as the Living Buddha Ji Gong, the latter a reference to the fact that Daoji had been exalted to the status of a deity after his death (already during his lifetime Daoji was recognized as a reincarnation of the Taming Dragon Arhat, one of the eighteen legendary arhats of Buddhism, an arhat being one who has attained the ultimate goal of enlightenment, or nirvana, by following in the footsteps of Buddha). Jigong, who championed the cause of ordinary people, was something of a folk hero. It was these qualities which caused people to see Daoji/Jigong as the reincarnation of the aforementioned beloved arhat.
But Mount Tiantai is more than simply a place of religious pilgrimmage. It is a lush green paradise that is known for its serenity and its cool summer climate, a feature that makes the area popular with tourists in search of refuge from the summer heat. There are more than a dozen scenic areas on Mount Tiantai - including religious sites - such as Guoqing, Chicheng, Fuolong, Shiliang, Huading, Zhang Qongtai, Tongkeng Stream, Ten Thousand Year Temple, Peach Land (to Chinese ears, "peach land" is synonymous with "paradise", both because of the fruit and the blossom), Clear Stream, Kaiyan-Zining, Lake Hanshan, Minghan Rock and Jiuzhe Mountain. All of these scenic areas have their own unique characteristics. Two absolutely must-see sites are Shiliang Flying Waterfall, at the Shiliang site, and Clouds Around Huading Peak, at the Huading site.
* Generally speaking, Buddhists do not revere physical landscapes such as mountains, rivers, lakes, etc. In India, such places are revered only where they have a direct connection to the Buddha, a bodhisattva, or an arhat. For example, almost all places ever visited by Shakyamuni Buddha are considered holy. The reason why mountains are revered for themselves - i.e., simply as holy mountains in and of themselves - in Chinese and Tibetan Buddhism, is owing to the incorporation of earlier religions into the particular Buddhism that eventually emerged in these two countries. These pre-Buddhism religions in China and Tibet (the Pre-Bön and Bön religions in Tibet, and Taoism/ Daoism in China) had incorporated elements of even earlier, more primitive belief systems that were grounded in filial piety (the worship of ancestors) and in animism, i.e., the belief that all things - animate as well as inanimate (including mountains) - possess a spirit.
As indicated above, the "interpretation" of Buddhism by Zhiyi went a long way toward making Buddhism accessible to the Chinese people; the incorporation of Taoist beliefs and practices into Chinese Buddhism and the similar incorporation of Pre-Bön and Bön beliefs and practices into Tibetan Buddhism were perhaps even more important agents in helping the peoples of these two cultures to embrace Buddhism.