1. A timepiece comprising: (a) a timepiece movement; (b) a dial; (c) time indicator members; (d) a lunar moving part driven by the timepiece movement and performing one revolution during an integral number of synodic months; (e) calendar indicator members that are movable relative to the dial; and (f) a calendar mechanism driven by the timepiece movement and comprising a moving part for months that completes one revolution per ordinary year and per leap year, wherein the calendar is a lunar-solar calendar comprising ordinary years comprising twelve lunar months and leap years comprising thirteen lunar months, and wherein the moving part for months is driven by the lunar moving part.