Capital-city land area is a weird metric: it depends almost entirely on where the official city limits were drawn. Beijing's 16,000 km² includes vast rural municipalities; Paris's 105 km² stops at the Périphérique. Vatican City is the smallest sovereign capital on Earth, smaller than most college campuses.

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Chinese and Australian capitals tend to be far larger than European ones because they include surrounding hinterland. Capitals in densely populated nations (Tokyo, Singapore) are surprisingly compact. African capitals vary wildly — Abuja was master-planned and is much larger than expected; Banjul, Gambia's capital, sits on a tiny island.