India's largest library hides a secret room discovered during a 2010 restoration project

Cultures · Published 30 September 2026 Swipe more like this →

In short: Housed in the former residence of British Viceroys, the National Library of India holds over 2.5 million volumes. Yet, its most intriguing feature isn't a book, but a sealed, windowless ground-floor chamber discovered by engineers in 2010, sparking wild theories about hidden treasure and colonial-era punishment cells.

The National Library of India, located in the Belvedere Estate in Kolkata, serves as the nation's primary repository for printed materials. Its origins trace back to the 1836 establishment of the Calcutta Public Library, a pioneering institution intended to support Western education for locals. Unlike its exclusive predecessors, which restricted access to British elites, the Calcutta Public Library was founded through the joint efforts of Western-educated Indians and British colonial officers. It was governed by proprietors, including prominent industrialist Dwarkanath Tagore, who paid 500 rupees to support its operations.

By the late 19th century, the library faced decline and underutilization, eventually merging with the Imperial Library under the 1902 Imperial Act. Following India's independence, the institution was renamed the National Library in 1948 and relocated to its current site in 1953. Today, it operates under the Ministry of Culture, mandated by the 1954 Delivery of Books and Newspapers Act to receive copies of all publications produced within India. Its vast collection includes 86,000 maps and 3,200 manuscripts, spanning at least fifteen languages.

The library's physical structure remains a subject of fascination. During a 2010 restoration by the Archaeological Survey of India, conservationists found a mysterious 1,000-square-foot room with no visible entrance. While speculation initially swirled regarding its potential use as a treasure vault or a site for colonial-era punishments, subsequent investigation in 2011 revealed the space was packed with mud, likely to stabilize the building's foundation. More recently, the library has embraced modern engagement, inaugurating the 'Museum of Word' in 2026 to showcase India's 22 official languages through interactive technology.

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