The city, because of its location and natural geography, has through history been a place of strategic military significance. The first fortifications were built as early as the 10th century. By the end of the 12th century, as the city expanded westward around the new St. Nicholas Church (today the Cathedral of Notre Dame), new walls were built that included an area of . In about 1340, under the reign of John the Blind, new fortifications were built that stood until 1867.