The building predates the museum by 85 years. Completed in 1922 during the reign of King Vajiravudh, Rama VI, it was designed by Mario Tamagno, an Italian architect who arrived in Siam in 1900 under a 25-year government contract. Tamagno had graduated from Turin's Albertina Academy of Fine Arts and studied under Carlo Ceppi before the Siamese government recruited him. His portfolio across two reigns reads like a catalog of Bangkok's most significant public buildings: the Ananta Samakhom Throne Hall, Abhisek Dusit Throne Hall, Parusakavan Palace, and the first office of Siam Commercial Bank, among many others. For the Ministry of Commerce, Tamagno collaborated with engineer E.G. Gollo, architect Guadrelli, and decorator Vittorio Novi to create a classical revival structure built of reinforced concrete -- advanced construction for its era, designed with fire prevention and heat ventilation in mind. The building received the ASA Architectural Conservation Award in 2006.

The building's bureaucratic journey mirrors the country's own institutional evolution. It opened as the Ministry of Commerce headquarters, then became the Ministry of Transport after a government reorganization, then reverted to the Ministry of Commerce in 1972. In 1999, the Ministry relocated to a new building, and the classical revival structure on Sanam Chai Road sat quiet. The Fine Arts Department registered it as a national heritage site in 2005. Between 2005 and 2007, the National Discovery Museum Institute undertook a careful project: assessing the building's structural condition, conducting archaeological excavations on the grounds (which had once belonged to a palace serving as residence for sons of King Rama III), and developing the exhibition content that would fill its rooms. The land beneath the museum holds layers of Bangkok's royal past that the conservation team documented before the public ever walked through the doors.

The museum's permanent exhibition, "Decoding Thainess," stretches across 14 zones, each approaching Thai identity from a different angle. The Thai Chim Room is a living kitchen where visitors scan QR codes to unlock the origins of Tom Yum Goong, Pad Thai, and Som Tam through colorful motion graphics. In the Thai Institution Room, augmented reality transforms a jigsaw puzzle into images representing nation, religion, and monarchy -- the three pillars of Thai civic identity. The Thai Only Room gathers household items that are unmistakably Thai: condiment bundles, coffee bags tied with rubber bands, Mama instant noodles in every flavor, and a four-meter-tall Nang Kwak beckoning statue. The Thai Dee Kot Room traces how foreign influences shaped Thai identity -- from the prang of Wat Arun to Thai script to the tuk-tuk -- using 3D laser cuts and zoetropes. Each room invites participation rather than passive observation, and the effect is a museum that feels more like a national conversation than a lecture.

The Sanam Chai MRT station, opened in 2020, deposited modern Bangkok directly at the museum's front door. The station is one of the Blue Line's most architecturally considered stops, designed to complement the historic surroundings of Rattanakosin Island. For a museum dedicated to exploring what Thailand was and is becoming, the transit connection carries symbolic weight -- linking the old administrative heart of Bangkok to the commuter networks of its sprawling modern self. Inside, the Thai Science Room recreates classrooms from four eras: the dawn of democracy, the 1950s, the globalization period, and the sufficiency economy era, each reflecting how national identity was transmitted through textbooks and songs. The Thai Chae Room offers a photography studio where visitors dress in period clothing and accessories. History here is not something you read on a wall. You try it on, taste it, and take a picture of yourself inside it.