For San Domingo was used to be called Hongmau Castle, because Taiwan people called the Dutch people Hongmau (people with red hair). The Castle is officially designated a historical site of the first-grade by the Republic of China's Ministry of Interior Affairs .
It is one of the oldest buildings surviving on the island, and is a relic of the Spanish and Dutch occupations of Taiwan in the early seventeenth century. The fort later passed through the hands of the Ming loyalist Zheng Cheng-gong (Koxinga), the Ching dynasty authorities and the British. Only in 1980 did its ownership finally revert to the Republic of China, Taiwan. To visit Fort San Domingo today is like reading a 350-year-long history of Taiwan.
Fort San Domingo is well preserved today, and its environs are pleasantly tranquil. Within the site are to be found the main building of Fort San Domingo itself, the building of the former British consular residence, and other items of historical interest such as the southern gateway of the enclosure and a number of antique cannons. The main entrance to the site is by the southern gate. This is a small castellated gateway built of stone quarried from Mountain Kuan-yin. It is extremely sturdy and remains the only wholly Chinese edifice surviving on the site today. The fort's architecture has considerable historical, cultural and artistic value, and also illustrates many technical features involved in the western construction of fortifications in the seventeenth century.
The main fort building is a square tower with an outer wall of red brick, topped by a parapet with embrasures and two corner watchtowers with firing slits. Its interior ceilings take the form of domed vaults, quite different from normal Chinese buildings. The pointed roof might have been made of wood by Dutch and equipped with cannon for defense. The walls are extremely strong and thick, massive enough to withstand cannon fire. This building was completely by the Dutch on a foundation left by the Spanish, and dates from over 340 years ago. The second floor of the main building was divided into offices for the consul, the assistant consul, and the others staff members. On the ground floor were four dungeons, and next to them was an open space divided into two parts: one for prisoners to take a walk and the other for the kitchen and the bathroom. Those in jail were mostly British or sailors from other western countries.
Considered as a whole, Fort San Domingo exhibits a blend of Dutch and British architectural styles. It is sturdily built and rises majestically on the skyline dominating the Tamsui River, a silent witness to Taiwan's historical past.

Just to the east of Fort San Domingo itself lies a fine western-style brick building, originally the British consular residence. It was built in 1891 in true nineteenth century colonial style. In 1867 the British rented Fort San Domingo from Ching dynasty to be used as their consulate in Tamsui. In addition to taking care of the British people in Taiwan, the consulate was mainly in charge of customs taxation, information collecting, and other international affairs. With the soaring export of tea leaves and camphor products, the status of the Tamsui harbor was increasingly important. The British government thus built the consul\'s official residence on the east side of the fort in 1877. The British consulate was temporarily closed during World War II . Then in 1980, the consular residence along with Fort San Domingo was returned to the government of the Republic of China, Taiwan .
The facade of the consular residence was distinguished by its Victoria style: red-brick structure, cloisters, an oblique roof, and a high staircase. The delicate red bricks were said to be hand-made and imported from Mainland China , and the lime material between the layers of bricks was a mixture of oyster shells, sticky rice, and black sugar water, which made the brick firmly consolidated after being dry. The front wall was decorated with twelve elaborately-made brickworks, featuring the British national flower and “VR 1891” (indicating the residence was built during the reign of queen Victoria in 1891). All the rooms of the residence were so well-furnished that they provided the consul and his family with cozy and secure place to relax and enjoy a traditional British lifestyle
Nearby there are Old Oxford School, Residence of Dr. Mackay and Tamshui College. These old buildings are mostly well preserved. When one walks among these buildings, he (she) would feel that times have turned back. One can enjoy the old streets, the cool breeze, the flower/trees planted by residents and the sense of relaxation. Walking on the old streets along the riverbank, visitors may view the old buildings and may try the tasty local dishes, such as fish dumplings, Argi (fried meat pastry) and hard eggs, etc. The dock is a good place for marvelous sunset viewing.