Wikipedia
In Jainism, a Bhonyra is an underground chamber in some Jain temples. In the past, it was used to conceal sacred idols during times of disturbance.
Naya Mandir in Delhi has a concealed chamber. A visitor in 1876 described it:
In Delhi I found a Jain temple which was wholly unknown to Europeans well acquainted with the city; and on prosecuting inquiry, I got its priest to open to me a concealed chamber containing large statues of several of the Tirthankaras richly ornamented.
The chamber has now been given the form of a cave, suitable for peaceful meditation by visiting Jain monks.
There are several Jain temples in Bundelkhand that have a bhonyra chamber. A few years ago, several Jain idols were found in a bhonyara in Sanganer in Rajasthan.
In 2001, an entire Jain temple was found beneath a mound at Umta, Gujarat. It was apparently buried to protect it from the destruction about 800 years ago.