The Hall of Nations | Courtesy of Raj Rewal AssociatesThe Hall of Nations, designed by Raj Rewal in collaboration with Mahendra Raj, embodied Indias post-independence modernist aspirations. As a key component of the Permanent Exhibition Complex in Pragati Maidan, New Delhi, it was constructed to mark the 25th anniversary of Indian independence in 1972. Unlike conventional exhibition halls, the Hall of Nations pioneered innovative material and structural solutions, standing as one of the worlds largest cast-in-situ concrete space frames.Hall of Nations Technical InformationArchitects1-8: Raj RewalLocation: Pragati Maidan, New Delhi, IndiaArea: 14,200 m | 152,847 Sq. Ft.Project Year: 1970 1972Demolition Year: 2017Photographs: See Caption DetailsThe Hall of Nations was conceived as an example of intermediate technologyneither completely traditional nor industrialreflecting Indias aspirations to bridge modernity with local ingenuity. Raj RewalHall of Nations PhotographsCourtesy of Raj Rewal Associates Ariel Huber Ariel HuberCourtesy of Raj Rewal Associates Ramesh LalwaniCourtesy of Raj Rewal AssociatesCourtesy of Raj Rewal AssociatesCourtesy of Raj Rewal AssociatesCourtesy of Raj Rewal AssociatesCourtesy of Raj Rewal AssociatesStructural Innovation: A Space Frame in Cast-in-Situ ConcreteFrom its completion, the Hall of Nations symbolized Indias aspiration to integrate technological advancement with local ingenuity. However, despite its architectural significance, the structure was demolished in 2017, raising serious concerns about preserving modernist heritage in India. At its core, the Hall of Nations was an unconventional experiment in structural geometry. While the space frame system was typically executed in steel or precast concrete, Rewal and Mahendra Raj pioneered an alternative method using cast-in-situ reinforced concrete, adapting to the limitations of Indias industrial capabilities in the early 1970s.The decision to use cast-in-situ concrete rather than steel was not purely aesthetic; it was a strategic adaptation to Indias then-limited prefabrication infrastructure. The structure was envisioned as a self-supporting geometric system, where each member was poured and set in place, eliminating the need for extensive formwork and temporary support.The Hall of Nations was structured using a truncated pyramid-based modular system, with each unit composed of rhombic cross-sections. This allowed for a self-supporting network of interlocking elements, ensuring that the overall form remained lightweight and structurally efficient. The pyramid geometry was not arbitraryit maximized stability while allowing for a column-free interior, a critical requirement for an exhibition space.One of the most remarkable aspects of the Hall of Nations was the resolution of complex nodes where multiple structural members converged. Some nodes accommodated up to twelve intersecting members, demanding precise reinforcement detailing to prevent material congestion and structural failure. Furthermore:A scaffolding strategy was implemented to support the structure only up to level five, beyond which the frame became self-supporting.Manual calculations were used extensively, as computational modeling tools were not available then.The final rhombic cross-section of the members was derived through an exhaustive study of geometry and structural efficiency.These choices resulted in a highly efficient structure in both material use and construction logistics, reinforcing the Hall of Nations as an architectural and engineering marvel.Spatial and Climatic Considerations: A Reinterpretation of the Indian JaliCourtesy of Raj Rewal AssociatesCourtesy of Raj Rewal AssociatesBeyond its structural innovations, the Hall of Nations was deeply attuned to the climatic conditions of New Delhi. The perforated geometry functioned as a passive climate control system, similar to the traditional Indian jali screens, which have been used for centuries to regulate building heat and airflow.The triangular openings in the space frame were designed for aesthetic reasons and also to filter sunlight while ensuring natural ventilation. This passive cooling strategy significantly reduced the need for mechanical air conditioning, a crucial advantage in Delhis hot climate.With a clear span of 78 meters, the Hall of Nations provided a large, uninterrupted interior space capable of accommodating a wide variety of exhibitions, from books to industrial machinery. The absence of internal columns ensured that exhibitors had complete freedom in configuring display layouts, making it a truly flexible space.The building featured eight pivoted steel gates, each leading to staircases and ramps. These multiple access points encouraged fluid movement between levels, allowing visitors to experience the structure from different vantage points.The Legacy of an Unprecedented Structure: Lessons for Future ArchitectsThe Hall of Nations was not merely an exhibition space; it was an ideological statement on the possibilities of modernist architecture in India. However, its legacy remains bittersweet, as its demolition in 2017 underscored Indias ambivalence toward preserving modern architectural heritage.The Hall of Nations contradicted Western expectations of space-frame structures when it was built. Figures such as Buckminster Fuller questioned the feasibility of using cast-in-situ concrete instead of steel. However, Robert Le Ricolais recognized the ingenuity of Rewal and Rajs approach and invited them to present their work at the University of Philadelphia.Rewal and Mahendra Rajs approach championed intermediate technology, a hybrid system that bridged traditional craftsmanship and industrial methods. This methodology remains highly relevant today, particularly in regions where full-scale prefabrication is neither economically nor technologically viable.The demolition of the Hall of Nations in 2017 ignited a global conversation on the importance of preserving modernist heritage. Its loss serves as a cautionary tale about the vulnerability of post-independence architecture, highlighting the need for stronger legal frameworks to protect 20th-century landmarks.As architects today grapple with sustainability and material limitations, the Hall of Nations remains a valuable reference point. Its design principlespassive climate control, modularity, and structural efficiencyare more relevant than ever, urging contemporary designers to reconsider the architectural and environmental implications of their material choices.Hall of Nations PlansFloor Plan | Raj Rewal AssociatesElevations | Raj Rewal AssociatesSketch | Raj Rewal AssociatesModel | Courtesy of Raj Rewal AssociatesHall of Nations Image GalleryAbout Raj RewalRaj Rewal is a renowned Indian architect who integrates modernist principles with traditional Indian architectural elements. His work, characterized by geometric precision, modular systems, and climatic responsiveness, reflects a deep understanding of cultural context and material efficiency. Notable projects such as the Hall of Nations (1972) and the Asian Games Village (1982) showcase his expertise in large-span structures and urban-scale planning, making him a key figure in post-independence Indian architecture.Credits and Additional NotesStructural Engineer: Mahendra RajClient: India Trade Promotion Organisation (ITPO)Main Hall of Nations: 6,700 m | 72,118 ftFour Smaller Halls of Industries: 7,500 m | 80,729 ftStructural System: Cast-in-situ reinforced concrete space frameClear Span: 78 meters (255 feet)Overall Height: 30 meters (98 feet) truncated at the roofBasic Structural Module: Truncated pyramid with a 4.9m x 4.9m base and 3.5m height