Sacred places in Islam are located at "shrines" important in the life of Muhammad, and the development of Islam.  They are normally ;located in Mosques.

The most sacred place for Muslims is the Ka'bah sanctuary at Mecca, the object of the annual pilgrimage.

The Ka'bah or Kaba is much more than a mosque; it is believed to be the place where the heavenly bliss and power touch the earth directly.

According to Muslim tradition, the Ka'bah was built by Abraham.

The Prophet's mosque in Medina is the next in sanctity. 

The third most important Holy Place for Muslims is the Dome of the Rock Mosque in Jerusalem.  This is the place where Muslims believed that Muhammad ascended into heave after his death.  Jerusalem follows in third place in sanctity as the first qiblah (i.e., direction in which the Muslims offered prayers at first, before the qiblah was changed to the Ka'bah) and as the place from where Muhammad, according to tradition, made his ascent (mi'raj) to heaven.