This is a massive gateway set in thick walls, largely ruined now, with sculptures of two warriors of the epic Mahabharat War: the Pandav brothers Arjun and Bhim. It is difficult to explain the presence of this gate unless one believes that the whole of the upper part of the island was once fortified. Or, perhaps, this led to a great temple, now destroyed.
A flight of over 200 steps winds down from this gate to the ghats. Pilgrims will then return to the Omkareshwar Temple to complete their parikrama, having walked around all the significant shrines and temples on the holy island. If they have done the complete parikrama they will, in effect, have walked an enormous OM. This must, surely, have earned for them considerable reserves of merit.