Tower of the Sun

The Tower of the Sun (太陽の塔, Taiyō no Tō) is an avant-garde sculpture and building created by Japanese artist Tarō Okamoto. Standing approximately 70 meters tall, it served as the symbol of Expo '70 and is currently preserved in Expo '70 Commemorative Park in Suita, Osaka Prefecture, Japan. The structure features multiple faces on its front and back, embodying a complex temporal and philosophical vision. In 2020, it was designated a Tangible Cultural Property of Japan, and the Osaka Prefectural Government has expressed interest in seeking UNESCO World Heritage inscription.

Tarō Okamoto designed the tower for Expo '70, and it was originally housed within the central Festival Plaza building known as "Big Roof" (大屋根), designed by architect Kenzō Tange. The tower's tip projected through a circular hole in Big Roof's ceiling due to its height. The name originated from an encounter with science fiction writer Sakyo Komatsu, who compared the protruding tower to a scene in the 1955 novel Season of the Sun where a character thrusts his penis through a sliding paper door; Okamoto adopted the suggestion.

During the exposition, the tower was open to the public, with visitors able to enter its interior. After Expo '70 concluded, it was closed. Big Roof was dismantled in 1979, leaving the tower exposed to the elements. Deterioration led to a demolition proposal, but preservation efforts prevailed. Repair work began in November 1994 and concluded in March 1995.

Limited interior openings occurred from 2003, including a lottery-based opening on October 11-12, 2003 for 1,970 people that drew over 24,000 applicants. Similar irregular openings continued until October 2006, attracting over 40,000 visitors total. Preparation for the 40th anniversary in 2010 led to another closure. After delays, permanent public reopening occurred in March 2018 with earthquake reinforcement, a restored Tree of Life, and a reconstructed "Sun of the Underworld." In 2016, Osaka Prefecture allocated 1.7 billion yen for interior restoration.

The Tower of the Sun functions as both sculpture and exhibition space, its interior conceived as an total artwork integrating architecture, sculpture, and kinetic display. The central holding is the "Tree of Life" (生命の樹, Seimei no Ki), a 41-meter-tall artwork representing the evolution of all creatures. Tsuburaya Productions produced the figurines featured in this installation. The tower originally contained escalators and elevators surrounding the Tree, with one elevator leading to the ceiling of Big Roof through an open wall; this was closed after the Expo. The interior was designed to be experienced through movement, with visitors ascending through evolutionary time.

The philosophical program extends beyond biological evolution to encompass human spiritual and technological condition. Art historian Fumihiro Sunahara has interpreted the Tower as Okamoto's rebellion against the Expo '70 theme of "Harmony and Progress for Mankind," arguing that Okamoto believed humanity had achieved progress and harmony only superficially and viewed unchecked technological advancement as naive. Akiomi Hirano, director of the Taro Okamoto Memorial Museum, similarly notes that Okamoto and the Tower opposed "optimistic futurism" and "the cult of technology," disagreeing with the exposition's mainstream technological optimism.

The Tower of the Sun presents three permanent faces, each carrying distinct temporal symbolism. The "Golden Mask" at the top, 11 meters wide, represents the future; an antenna protruding from its mouth serves as a lightning rod. The "Face of the Sun" on the front between the two 25-meter-long arms represents the present. The "Black Sun" on the back represents the past, symbolizing a sun "scientifically analyzed by humans" and nuclear energy.

A fourth face, the "Underground Sun" or "Sun of the Underworld," originally existed in a subterranean space titled "PRAYER" during Expo '70. This face expressed "the inner spiritual world of humans" rather than a temporal aspect. It disappeared after the Expo and was moved to an unknown location; the original has never been found, though a reconstruction has been exhibited since 2018.

The Tree of Life remains the signature interior work, featuring 292 different models of living organisms attached to its trunk and branches, with large illuminated amoebas at the bottom and humans at the top, smallest in scale. The jagged red paintings on the tower's front represent thunder.

A miniature version of the Tower of the Sun is held at the Taro Okamoto Museum of Art. The tower has been listed among the Best 100 Media Arts in Japan by the Agency for Cultural Affairs.

The tower measures approximately 70 meters in height, 20 meters in base diameter, with two arms extending 25 meters each. Its exterior was constructed using shotcrete, deliberately left bumpy to achieve a "natural texture" rather than an industrial surface. The structural material is steel reinforced concrete.

The lighting system in the Golden Mask's eyes has undergone significant evolution. Xenon arc floodlights were used during Expo '70 but were later deactivated due to electrical problems and concerns about disrupting operations at nearby Osaka Itami Airport. On September 25, 2004, an external battery connected new lights for a countdown to Expo 2005. In 2010, the floodlights were replaced with 148 lower-brightness LEDs.

The Golden Mask itself has been replaced: the original was constructed from 337 steel plates, but deterioration from wind and rain led to installation of a second-generation stainless steel replica in 1992. Approximately half of the mostly undamaged original plates remain in storage within Expo '70 Commemorative Park.

The tower is situated within the Natural and Cultural Gardens of Expo '70 Commemorative Park in Suita. The removal of Big Roof in 1979 fundamentally altered its relationship to the site, transforming it from an enclosed element to an exposed landmark.

The Tower of the Sun is located in Expo '70 Commemorative Park in Suita, Osaka Prefecture, Japan. Its official website is https://taiyounotou-expo70.jp/. The interior, closed for decades after Expo '70, was permanently reopened to the public in March 2018 following earthquake reinforcement and restoration work, though access may require advance reservation. The tower is owned and managed as part of the commemorative park facilities.

The structure's current role extends beyond tourism to cultural symbol and potential World Heritage candidate. The Osaka Prefectural Government has actively pursued UNESCO World Heritage inscription, announcing this intention in 2018. Its designation as a Tangible Cultural Property of Japan in 2020 formalized its national significance. The tower continues to function as a site of pilgrimage for understanding postwar Japanese avant-garde art and the critical legacy of Tarō Okamoto.