Book excerpt: As a strategically located seat of European power, Paris was a prized target for invaders. Consequently, it was one of the world's most heavily fortified cities. Though many of the fortifications have been demolished, or hidden, they have left their imprint on the city, both physically and historically. To understand the history of Paris--and indeed, of France as a whole--one must understand the history of the fortifications. This heavily illustrated history begins with the period 300 B.C. to A.D. 987. Part II looks at the Medieval era (987-1512), a growth period for the city. Bastioned fortifications (1512-1874) are the focus of Part III, covering the era in which Paris modernized its defenses. Modern fortifications (1874-1944) are detailed in Part IV, ranging from the building of the second Parisian ring of polygonal forts to the end of World War II.