The guitar originally had four courses of strings, three double, the top course single, that ran from a violin-like pegbox to a tension bridge glued to the soundboard, or belly; the bridge thus sustained the direct pull of the strings. In the belly was a circular sound hole, often ornamented with a carved wooden rose. The 16th-century guitar was tuned C–F–A–D′, the tuning of the centre four courses of the lute and of the vihuela.