fortifications [ˌfɔ:təfə'keɪʃənz]

例句:

• The emperor and his court enjoyed...the security of the...fortifications.
  来自Gibbon
• Fortifications were therefore required in the environs of New Orleans.
  来自NEWYORKER
• The government has started building fortifications along its eastern border.
  政府已经开始沿东部边境修筑防御工事。
  
• the ramparts and fortifications of the Old Town
  旧城区的城墙和城堡
  
• The fortifications were out of repair.
  防御工事年久失修.
  
• The compound stands out on one of Tehran's main avenues with its high walls, barriers and fortifications.
  来自BBC