The tomb of Kien Thai Vuong Nguyen Phuc Hong Cai (1845-1876) is located on Cu Si Mountain in Thuy Xuan Ward, surrounded by a green pine forest. The tomb lies close to the tombs of emperors Dong Khanh and Tu Duc.

Kien Thai Vuong Nguyen Phuc Hong Cai was a prince, son of Emperor Thieu Tri. While he did not rule, he was the father of three Nguyen Dynasty emperors: Kien Phuc (Nguyen Phuc Ung Dang), Ham Nghi (Nguyen Phuc Ung Lich), and Dong Khanh (Nguyen Phuc Ung Ky). He was also the grandfather of Emperor Khai Dinh and the great-grandfather of Emperor Bao Dai.

He passed away at just 31 years old, and his tomb was constructed on a smaller scale than those of the Nguyen Dynasty emperors. The tomb complex is enclosed by a system of enclosure walls, lacking the grand palaces and large courtyards found in imperial tombs.

After ascending the throne, Emperor Dong Khanh instructed the Ministry of Public Works to build Dien Truy Tu nearby to enshrine his father's ancestral tablet for worship. He also ordered the complete construction of his father's tomb. However, Emperor Dong Khanh passed away suddenly in 1889 while the work was still under construction. Dien Truy Tu was subsequently renamed Dien Ngung Hy, becoming a place of worship for Emperor Dong Khanh.

The tomb of Kien Thai Vuong features intricate ceramic mosaic art. Its architectural structure, from the outside in, includes the tomb gate, front screen, stone altar, tomb chamber, and rear screen. The front screen of Kien Thai Vuong's tomb is adorned with numerous "Tho" (longevity) characters in ceramic mosaic. This character is common in ceramic mosaic art found in Nguyen Dynasty tombs, symbolizing eternal existence.

The tomb of Kien Thai Vuong is built similarly to the tombs of Nguyen lords, featuring a rectangular, two-tiered structure. In front of the tomb is a Thanh stone altar, and behind it is a screen.

Two exquisitely carved Thanh stone dragon statues flank the entrance to the tomb.

Both sides of the enclosure wall are adorned with raised ceramic mosaic images of dragons and carp transforming into dragons.

In front of Kien Thai Vuong's tomb are two solidly built bi dinh (stela pavilions) featuring dragon-shaped ceramic mosaics.

The roofs of the two bi dinh are covered with yellow imperial glazed tiles, intricately carved with dragon motifs in ceramic mosaic, symbolizing the power of the Nguyen Dynasty.

A Thanh stone stela, housed within the bi dinh, bears an inscription acknowledging Kien Thai Vuong's contributions and affirming the respect of emperors Ham Nghi, Kien Phuc, and Dong Khanh for their father.

In front of the Kien Thai Vuong tomb area stands the Nghi Mon (ceremonial gate), decorated with cloisonne enamel art. Both sides are adorned with ceramic mosaic images of mythical creatures.

Following its restoration in 2023, Kien Thai Vuong's tomb has become a popular destination for many visitors, located more than 50 meters from Emperor Dong Khanh's tomb.

Vo Thanh