Wat That Tharam/Wat Khao That

The city chronicle already mentions a fortification when the town was reestablished in 1278. Restorations were recorded at the time of King Ramesuan (14th century), as well as King Narai (1686). The latter was aided by the French engineer, M. de la Mare. The walls spread 456 m from east to west, and 2,238 m north to south, enclosing an area of about one square kilometre. The northern wall had only one gate, called Prathu Chai Nua or Prathu Chai Sak. The southern wall had only one gate. To the east there were three gates, which connected the town with the sea. To the west were five gates. Today only the northern gate still exists, together with a short stretch of the northern city wall.

The museum has on display artifacts found in four southern provinces, Nakhon Si Thammarat, Phatthalung, Surat Thani, and Chumphon. There is a good collection of rare books and important books sent by the National Library in Bangkok.

The most important temple in Nakhon Si Thammarat and southern Thailand. It was constructed at the time of the founding of the town, and contains a tooth relic of Buddha. The 78 m high chedi is surrounded by 173 smaller ones. While the chedi is now in Sri Lankan style, it is said to have been built on top of an earlier Srivijaya-style chedi. At the base of the chedi is a gallery named Viharn Tap Kaset, decorated with many Buddha statues and elephant heads emerging from the chedi. Viharn Phra Song Ma is the buildings which contains the staircase which leads to a walkway around the chedi above the gallery. At the bottom of the staircase are demon giants (yak) as guardians. Adjoining to the north is the Viharn Kien, which contains a small temple museum. South of the chedi is the large ubosot building, the Viharn Luang. Living quarters are across the street in a separate temple, Wat Na Phra Boromathat. The chedi is the symbol of Nakhon Si Thammarat Province, prominent on the seal of the province. It is also displayed on the 25 satang coin. In 2026, this temple was inscribed as a .

Houses Luang Pho Phut, a red sandstone Buddha image from the Ayutthaya period. In addition, the temple houses a giant phallic symbol found at Khao Kha archaeological site and is believed to be around 1,200 years old. Formerly Wat Tai.