The Mausoleum of Moulay Idriss is Morocco's most important pilgrimage site, and the town is swamped every August during the annual moussem to venerate it; it’s said locally that five pilgrimages to Moulay Idriss during the moussem equals one hajj to Mecca. The entrance is located at the top of the town's main square, via a three-arched gateway surrounded by shops selling religious trinkets – non-Muslims cannot enter beyond the inner barrier, but it's worth a peak inside the grand entrance.
Moulay Ismail created this pilgrimage site by building the mausoleum during the late 17th and early 18th centuries in a successful attempt to rally the support of the faithful.