6. Ouvrages: These fortresses were the most important fortifications on the Maginot Line, having the sturdiest construction and the heaviest artillery. Source: Internet
Although the Karelian Isthmus front was less active in January than in December, the Soviets began increasing bombardments, wearing down the defenders and softening their fortifications. Source: Internet
After German Unification in 1871, Erfurt moved from the southern border of Prussia to the centre of Germany, so that the fortifications of the city were not needed anymore. Source: Internet
After the siege Memorial for Jean Parisot de Valette in Valletta The year after, the Order started work on a new city with fortifications like no other, on the Sciberras Peninsula which the Ottomans had used as a base during the siege. Source: Internet
After the disappearance of the Čakany and Velatice cultures, the Lusatian people expanded building of strong and complex fortifications, with the large permanent buildings and administrative centers. Source: Internet
Also, there had been a system of fortifications in pre-Viking Mercia that may have been an influence. Source: Internet