Located atop the Mundeshwari Hill (around 600 feet high) near Kaura village in the Kaimur district of Bihar, the Mundeshwari Devi Temple is considered by many historians and archaeologists to be one of the oldest functional Hindu temples in India, possibly the oldest. This claim is substantiated by significant archaeological and epigraphic evidence found at the site. Key inscriptions discovered here include one dated to Saka Era 30 (corresponding to 108 CE) and another crucial one dating to Gupta Era 30 (interpreted by some scholars as year 30 of a specific Gupta ruler, or possibly needing recalibration, but often cited as evidence of early Gupta presence, with another inscription clearly dated 635/636 CE during the later Gupta period). These inscriptions strongly indicate continuous worship at the site from at least the Saka-Kushan or early Gupta period onwards. Architecturally, the temple is unique for its octagonal plan, a rare design for ancient Indian temples, built entirely of stone blocks. The presiding deities within the temple are Devi Mundeshwari (considered a form of Shakti or Mahishasuramardini) and a remarkable Chaturmukha (four-faced) Shivalinga positioned in the center of the octagonal sanctum. Subsidiary deities and fragmented sculptures dating to the Gupta and later periods have also been found in the vicinity. The temple likely received patronage from local rulers serving as feudatories under larger empires like the Guptas and later dynasties. Its relatively remote hilltop location might have contributed to its survival through centuries of political turmoil and iconoclasm that affected temples in the Gangetic plains. Recognized by the Archaeological Survey of India, the Mundeshwari Temple stands as a vital historical monument, offering invaluable insights into early temple architecture, religious practices (Shaiva and Shakta worship coexisting), and epigraphic history in Bihar. It remains an active place of worship, attracting pilgrims especially during Navaratri and Shivaratri.