长城

Great Wall;impregnable fortress (or bulwark)
不到～非好汉。He who doesn’t reach the Great Wall is no true man. or:He is no true man who doesn’t carry sth to the end./解放军是祖国的钢铁～。The PLA is the bronze wall of our nation./～是世界奇观之一。The Great Wall is one of the wonders of the world.