A permit from the Ordnance Depot or the Tourist Office is required for visiting the Patalpuri Temple and the Akshaya Vat.
Patalpuri temple, one of the oldest and most famous temples in India, is an underground temple contained by the Allahabad fort. It is believed that lord Rama has visited this temple. And a famous Chinese traveler and writer Huan Tsang also visited it. The undying banyan tree or 'Akshayavat' within the Patalpuri temple has found state in the account of several ancient scriptures, writers and historians. The pilgrims used to throw themselves from this tree to achieve salvation.
This place of worship inside the Fort is an important place of pilgrimage. It dates from the epic age. Hiuen Tsang, the Chinese traveler who visited the Fort in 634 AD during his journey through India, mentioned its imprinted stone divinity. It became an underground holy place when Akbar construct his Fort over and around in 1583.
Currently, a sacred fig tree located within the Patalpuri Temple at the Allahabad Fort is worshipped as the Akshayavat described in ancient texts. As of 2011, a permission from the Commandant of Allahabad Fort's Ordnance Depot is needed to visit this tree. On one day during the Kumbh Mela, the site is open to all the pilgrims. However, a popular opinion is that the Patalpuri Temple tree is not the authentic Akshayavat: the real Akshayavat is in another underground temple inside the Fort. When the British gained control of the Allahabad Fort after the Treaty of Allahabad in 1765, they did not want general public to access the sensitive parts of the fort. So, the shrine was moved to fringes of the fort compound, that is, the present-day Patalpuri Temple. According to the Welsh travel writer Fanny Parkes, who visited both the tree sites in 1831, when the original Akshayavat chamber was closed, the local Brahmins set up the stump of a ber tree in Patalpuri. They claimed that it was a branch of the original Akshayavat that had penetrated through the walls, and made a lot of money from pilgrims visiting it during the fair. Parkes states that the local Hindus of Prayag knew about this "trick", and did not worship the false Akshayavat. An 18th century map of the Fort from the British Library confirms this: the location of the original temple is shown in the center of the fort; while the present-day Patalpuri Temple is on the outskirts of the Fort. In the 1950s, Shiva Nath Katju also claimed that the "tree" placed in the Patalpuri Temple was only a log that was replaced by the priests every 4–5 years. The commander of the fort acknowledged his claim as true.