Senses
长城/ 長城 Great Wall
The Great Wall of China; also refers more generally to a long wall or fortification.
长城/ 長城 pillar of the state
a person or group of people who can be relied upon as a mainstay of the country
长城/ 長城 impregnable defense
an unbreakable power, barrier, or fortress; can also refer to one's own status or position (figuratively) the mahjong wall