píng / jiè / xiǎn / yào / dì / xíng / zhè / zuò / chéng / fáng / shǒu / yán / mì / kān / chēng / jīn / chéng / tāng / chí

凭借险要地形，这座城防守严密，堪称金城汤池。

Thanks to its rugged terrain and strong defenses, the city was virtually impregnable.