De locis sanctis (Concerning sacred places) was composed by the Irish monk Adomnán, a copy being presented to King Aldfrith of Northumbria in 698. It was based on an account by the Frankish monk Arculf of his travels to the Holy Land, from which Adomnán, with aid from some further sources, was able to produce a descriptive work in three books, dealing with Jerusalem, Bethlehem, and other places in The Holy Land, and briefly with Alexandria and Constantinople. It aimed to give a faithful account of what Arculf actually saw during his journey. Many of the manuscripts contain the second earliest known map of Jerusalem (it was the earliest known map until the discovery of the Madaba Map.) The work contains the four earliest known drawings of Christian churches in the Holy Land; three are in Jerusalem (the Church of the Holy Sepulchre, the Church of Zion, and the Chapel of the Ascension) and one in Nablus (the Church of Jacob's Well). Source: Wikipedia (en)