城下
じょうか · jouka · JLPT N1 · noun
palace
城 — earth radical 土 + 成 (to complete)
Originally a semantic-phonetic compound: 土 (earth) gives the meaning, since ancient cities were defended by rammed-earth walls, while 成 supplies the sound. The earliest meaning was 'city wall,' which later broadened to 'walled city' and then simply 'city' or 'town.'
下 — horizontal line 一 + mark below
下 is an indicative character: a long horizontal line represents a reference level, and a shorter stroke placed beneath it points to the area below. The original meaning 'below, down' comes directly from this spatial diagram, and it later extended to verbs like 'descend' and 'lower'.