The uncontested surrender of the supposedly impregnable fort caused a public and political uproar.

Bhainsrorgarh is an impregnable fort, inhabited from at least the 2nd century BC.

Or had a neighbor come to claim rights to an impregnable flying fort?

Jalore Fort is regarded as one of the most impregnable forts of the country.

Block that up with native stone and this would be an impregnable fort.

It is a natural impregnable fort and stands on a hill, at an attitude of about 2430 metres above sea-level.

Ginnor was considered an impregnable fort, located at the summit of a steep 2000-foot high rock, and surrounded by thick forest.

The soldiers successfully create an impregnable fort on Banshee.

I shall not swiftly forget the fall of your impregnable forts.

It was he who made Mandu one of the most impregnable forts of India.