I struck against an impenetrable wall, and fell down upon the rock.

It was as if she'd built a very firm, impenetrable wall between them.

Safety was just the other side of an impenetrable wall.

What could be more simple than an apparently impenetrable wall?

It's not about building up an impenetrable wall but instead just getting by with what you have.

It would help her through spots like this, when she hit the impenetrable wall of culture.

Circumstance seemed to be building an impenetrable wall around her.

They seemed to form an impenetrable wall on either side of the aisle.

All his mind was bent on getting through or over this impenetrable wall and guard.

Still, the reserve that had built up between the two men, an impenetrable wall for the past five years, remained.