The Tsukahara Burial Mounds are a historic group of ancient tombs located in Tsukahara, Jonan-machi, Minami Ward, Kumamoto City, Kumamoto Prefecture. The site is particularly remarkable because part of the Kyushu Expressway passes directly beneath the burial mounds. This unusual arrangement was adopted to protect the archaeological remains when they were discovered during expressway construction.
The burial mounds were built between the 4th and 6th centuries and form one of the largest groups of ancient tombs in Kumamoto Prefecture. They are also considered one of the major burial-mound complexes in Japan. Historical records, including the Edo-period works Higo Koku-shi and Kokon Higo Kenmon Zakki, mention the site, demonstrating that its existence was known long before modern archaeological excavations began.
Archaeological investigations began in 1972 in connection with the construction of the Kyushu Expressway. Excavations uncovered numerous types of ancient graves, including circular burial mounds, square burial precincts surrounded by ditches, and keyhole-shaped burial mounds.
In 1976, the Tsukahara Burial Mounds were designated a National Historic Site of Japan. The area was subsequently developed as Tsukahara Burial Mound Park, where visitors can see reconstructed burial mounds and learn about the site’s history. Archaeological finds and related materials are displayed at the Kumamoto City Tsukahara History and Folklore Museum within the park.
Among the remains identified within the expressway construction area are 39 square burial precincts surrounded by ditches, 34 circular and small circular burial mounds, one keyhole-shaped burial mound, and 18 stone coffins. These finds reveal the variety of burial practices used in the region during ancient times.
The Tsukahara Burial Mounds are believed to extend beyond the land used for the Kyushu Expressway. A preliminary investigation conducted in 1975 confirmed that burial mounds were distributed across the Tsukahara Plateau and that settlements had also existed in the same area.
Investigations have identified a total of 203 burial mounds to date. When uninvestigated remains are included, it is estimated that nearly 500 burial mounds may exist throughout the area. This extensive distribution suggests that the plateau was an important place for communities living in the region during ancient times.
The 2016 Kumamoto Earthquake damaged parts of the site. A house-shaped stone coffin inside one of the burial mounds was broken, and some information boards fell down. Repair and conservation work has continued since the earthquake to protect the archaeological remains and preserve their historical value.
Tsukahara Burial Mound Park is a spacious public park developed around the burial-mound complex. Seventy-seven reconstructed burial mounds can be seen within the park, allowing visitors to appreciate the scale and variety of the ancient tombs.
The grounds are planted with seasonal flowers, including cherry blossoms, hydrangeas, and cosmos. Playground equipment is also available, making the park a place where local residents and visitors can enjoy both outdoor recreation and an encounter with ancient history.
Kumamoto City Tsukahara History and Folklore Museum: A museum displaying archaeological finds, historical materials, and exhibits about the Tsukahara Burial Mounds and the former Jonan area.
Hi no Kimi Amusement Park: An amusement facility located within the park grounds.
Kumamoto Prefectural People’s Observatory, operated by an NPO: An astronomical observatory that is open from Friday through Sunday. Reception hours are from 7:00 p.m. to 9:00 p.m.
The Kumamoto City Tsukahara History and Folklore Museum is located within Tsukahara Burial Mound Park. Plans for the museum were agreed upon in 1974 by the Agency for Cultural Affairs, Kumamoto Prefecture, the former Jonan Town, and the Japan Highway Public Corporation.
The museum opened in 1983 under the name Jonan Town History and Folklore Museum. When Jonan Town merged with Kumamoto City in 2010, the facility received its present name.
The museum has three exhibition rooms devoted to archaeology, history, and historical materials. Its displays introduce the Tsukahara Burial Mounds, archaeological finds from the former Jonan area, and objects related to local life and folk traditions. The museum serves as a center for sharing the area’s history and culture with residents and visitors.
Tsukahara Tunnel was constructed when the Tsukahara Burial Mounds were discovered during the building of the Kyushu Expressway in 1972. The original plan called for cutting through the hill to create the road, but a campaign to protect the archaeological site led to a different solution: a tunnel was built beneath the burial mounds to preserve them.
This approach was described as Japan’s first attempt to construct a tunnel beneath an ancient burial-mound site for the purpose of protecting cultural heritage. The tunnel is 340 meters long and represents an unusual example of how a major public infrastructure project was adapted to conserve archaeological remains.
The tunnel was designed to pass close to the ground surface so that the burial mounds above it could be preserved. Its cross-section is rectangular and it has no ceiling panels, giving it a structure different from that of many other expressway tunnels.
The tunnel’s name also has an interesting feature. The local place name is pronounced “Tsukawara,” while the tunnel’s sign uses the spelling “Tsukahara Tunnel,” reflecting a difference in pronunciation.
Protecting the burial mounds required substantial changes to the original construction plan. The work took two years longer than initially scheduled and increased construction costs by 2.6 billion yen. Nevertheless, the project demonstrated that cultural-property conservation and public infrastructure development could be achieved together.
Unlike the many tunnels in the mountainous sections of the Kyushu Expressway south of Yatsushiro Junction, Tsukahara Tunnel is located in a relatively flat area. Its unusual structure makes it a distinctive feature of the northern part of the expressway.
The Tsukahara Burial Mounds and Tsukahara Burial Mound Park can be visited freely. The History and Folklore Museum has its own admission fee and opening hours.
Adults: 200 yen
Elementary and junior high school students: 100 yen
The Kumamoto City Tsukahara History and Folklore Museum is open from 9:00 a.m. to 4:30 p.m.
The museum is closed every Monday. If Monday is a public holiday, the museum opens that day and closes on the following weekday instead.
The museum is also closed from December 29 through January 3 for the New Year holiday period.
From Sakuramachi Bus Terminal in central Kumamoto, take a Kumamoto Bus service bound for Shidoji, Shimo-Yasumi, or Danzuru via Jonan. Get off at the Tsukahara bus stop and walk approximately 8 minutes, or about 600 meters, to the site.
Alternatively, take a bus bound for Matsubase Station via Jonan, get off at the Kokaidomae bus stop, and walk approximately 20 minutes, or about 1.7 kilometers.
From JR Uto Station on the JR Kyushu Kagoshima Main Line, the site is approximately 15 minutes away by car.
Parking is available.
The Tsukahara Burial Mounds offer a rare opportunity to explore an extensive ancient cemetery while learning how modern infrastructure can be designed to protect cultural heritage. The reconstructed tombs, seasonal flowers, and museum exhibitions make the park accessible to a wide range of visitors, from history enthusiasts to families.
The nearby Tsukahara Tunnel adds another dimension to the visit. Its construction beneath the burial mounds illustrates the efforts made to preserve an archaeological site of national importance. Together, the park, museum, and tunnel tell a compelling story of ancient communities, modern archaeological research, and the continuing importance of protecting Japan’s cultural heritage.