The mausoleum of 5th Ottoman sultan Mehmed I Çelebi (and several of his children) stands in a cypress-trimmed park opposite Yeşil Camii (Green Mosque). During his short rule (1413–21), he reunited a fractured empire following the Mongols' 1402 invasion. Despite its name, the türbe (tomb) is not green; it has blue Kütahya tiles outside that postdate the 1855 earthquake. The structure has a sublime, simple beauty, the original interior tiles exemplifying 15th-century decor. There is also an impressive tiled mihrab.