Chongye valley:

Chongye Valley is also called the Valley of Kings. It branches off the Yarlung Valley to the southwest, and it contains eight large burial mounds. They look like round green hills from the outside, and it is not possible to enter them, however, the most important kings of the Yarlung dynasty are believed to be buried in them. It lies about 27 km from away from Tsetang,  and the largest mound considered to be the burial place of the first Buddhist king, Songtsen Gampo, has a 13th century reconstructed temple on top. Climb the hill on a stairway and visit the temple for an ancient atmosphere and a stunning view of the Valley of Kings.

Yumbu Lhakhang:

It is situated 9 km south of Tsetang. The beautiful citadel operating as a temple today is believed to be the palace of the first Tibetan king, Nyatri Tsenpo, who descended from the sky. It was a royal palace right up to the 7th century, when Songtsen Gampo decided to move his capital to Lhasa. The walk up on the steep stairway is easier than it looks,  but there are also horses for hire. From the Yumbu Lhakhang you get a fantastic view of the fertile Yarlung valley, the earliest cultivated area of Tibet.

Samye:

Samye is the first monastery of Tibet built in 775 AD by King Trisong Detsen, who tried to revitalize Buddhism by inviting monks from India and supporting the translation of scriptures from Sanskrit into Tibetan. There are many Buddhist legends related to Samye. One says, that Shantarakshita, the Indian master of Buddhist philosophy asked the king to invite Guru Rinpoche (Padmasambhava), the Indian Tantric master to subjugate the indigenous deities and spirits of Tibet in order to allow the spread of Buddhism. Guru Rinpoche tamed the local deities and spirits, and forced them to take an oath to protect the Buddhist teaching. This is how the local deities became integrated into Tibetan Buddhism. The Samye Monastery was the place where in about 792 a debate was organized to decide if Tibet should follow the Chinese teachings of Buddhism (instant enlightenment) or the Indian tradition (gradual path). As the Indian master, Kamalashila won the debate, the Indian system of Buddhism spread in Tibet. Samye Monastery is laid out on the shape of a giant mandala, and its main temple, the Utse is symbolizing Mt. Meru, the central mountain of the Buddhist universe. From the top of the neighbouring Hepo Hill, you can get an almost aerial view of the mandala-shaped monastery.