There are two popular Tibetan verses in relation to Drak Yerpa

In addition to including such stereotyped visits covering Potala Palace, Jokhang Temple, Sera Temple, Norbulingka and so on, don’t forget to add an excursion to Drak Yerpa Monastery, which is located about 40km northeast to the city center of Lhasa.

There are two popular Tibetan verses in relation to Drak Yerpa. One verse says that “While Tibet‘s holy place is in Lhasa, Lhasa’s holy place is in Drak Yerpa”. Another verse goes like that “Visiting Lhasa without going to Drak Yerpa is just like making a new clothe without adding the collar”. These two verses pinpoint the importance of Drak Yerpa in the hearts of the common Tibetan pilgrims.
It is said that Songtsän Gampo and his two foreign-born queens have meditated in the 'Peu Marsergyi Temple' and in the 'Chogyel Puk'. People also said they had discovered 'self-originated' symbols of the Buddha-body, speech and mind. Another famous person who meditated here is Padmasambhava, or Guru Rinpoche. He also practiced tantric yoga with his yogini Yeshe Tsogyal here. Totally he spent 7 months in meditation in the 'Dawa Puk', which is considered to be one of his three most important places of attainment. Several of Guru Rinpoche's disciples are also said to have meditated here.
Except working as a great meditation or hermitage place for Buddhist, the Dark Yerpa is also a commendable place for trekking. Trekking or bicycling to Drak Yerpa, you will get closer to the natural beauty in this place.     

The Gyantse Dzong is a medieval citadel situated in Gyantse

The Gyantse Dzong is Gyantse's town fort sitting upon a hill just north of Gyantse town on China-Nepal Hwy. Wherever you are in Gyantse, the Dzong can be seen. However, the fort lies abandoned today and many of its interior walls and buildings are in disrepair.

 
Gyantse Castle or Gyantse Fortress or Gyantse Dzong is a medieval citadel situated in Gyantse, Xigazê Prefecture in China. It was constructed in 1268 by a Sakyapa sect (one of many Buddhist schools) in the beginning of the Nyang Qu river. This strategic location guarded a Southern pass of the Tsangpo Valley and Lhasa. The entrance to the compound is on the Eastern side. Current citadel was constructed on a site of an older 9th century fortifications constructed by anti- Buddhist king Langdharma. Its name literally means "the peak of victory". Prince Phakpa Pelzangpo (1318- 1370) erected a Grand Palace Gyantse in 1365 and his son Kungpa Phakpa (1357- 1412) added new fortification walls. Gyantse Castle harbors an "anti- British" museum devoted to British invasion of 1903- 04.

The fort is partly ruined, but there are still some things to see. There is an interesting Anti-British Imperialists Museum here displaying a version of the facts of the 1904 British invasion of Tibet and a major battle that took place. The British used massive firepower to defeat a much less powerful Tibetan army here and a part of the fort was blown up during the battle.
The half hour climb up to the fort is well worth it, as the spot offers fantastic vistas of the monastery compound to the north, the town below, and the surrounding valley.  

Tashilhunpo Monastery is a historic and culturally important monastery next to Shigatse

  Tashilhunpo Monastery, founded in 1447 by Gendun Drup, the First Dalai Lama, is a historic and culturally important monastery next to Shigatse, the second-largest city in Tibet. It was sacked when the Gurkhas invaded Tibet and captured Shigatse in 1791 before a combined Tibetan and Chinese army drove them back as far as the outskirts of Kathmandu,when they were forced to agree to keep the peace in future, pay tribute every five years, and return what they had looted from Tashilhunpo.

  The monastery is the traditional seat of successive Panchen Lamas, the second highest ranking tulku lineage in the Gelukpa tradition. The "Tashi" or Panchen Lama had temporal power over three small districts, though not over the town of Shigatse itself, which was administered by a dzongpön (prefect) appointed from Lhasa.
  Located on a hill in the center of the city, the full name in Tibetan of the monastery means: "all fortune and happiness gathered here" or "heap of glory".
  Tashi Lhunpo Monastery is a nonprofit charitable organization which imparts various aspects of the Buddhist religion while maintaining a school of modern education. In recent years it has matured into a reputable full-fledged monastery, performing a vital role in the preservation of Buddhism. One aspect of a monastery is the parental-like responsibility of looking after the physical, mental and spiritual well-being of all the monks, throughout their lives. The modern school is at the budding stage and faces enormous daily hurdles. Yet, there is faith in divine help as the school moves along.