Words similar to impregnable

Example sentences for: impregnable

How can you use “impregnable” in a sentence? Here are some example sentences to help you improve your vocabulary:

This route sits against the old city walls, which were completed in 1785, and from here it is easy to see why the city was thought to be impregnable.
The dramatically rising cliff of black basalt stone made the castle impregnable to all but the most wily commander.
Once a vast fortification of 49 turrets, it ranked alongside Osaka and Nagoya as one of the country’s greatest impregnable bastions.
The Moors were on the retreat, withdrawing to the almost impregnable mountain fortress area of Granada, where they held out until 1492.
Surrounded by a pair of precipitous ravines, the imposing walls of the citadel were some forty feet high and twenty feet thick, virtually impregnable.