京城 literally means 'capital city'—'京' (jīng) refers to the imperial capital or seat of supreme authority, and '城' (chéng) means 'city' or 'walled city.' Together, they form a formal, literary term for the national capital, historically used for cities like Chang'an, Luoyang, Beijing, or Nanjing during imperial dynasties. It carries classical elegance and solemnity, evoking historical grandeur and political centrality.

Today, 京城 is still used in writing, poetry, news headlines, and formal speeches—especially when referring to Beijing—but it’s not common in casual daily speech. Unlike the neutral term 首都 (shǒudū), 京城 implies cultural weight, tradition, and poetic resonance. It may appear in idioms, historical novels, or official documents emphasizing heritage and prestige, and is rarely used for non-Chinese capitals.