Here’s a suggestion for how to complete the text with the appropriate articles:

**THE GREAT WALL OF CHINA**

The Great Wall of China is one of (1) **the** wonders of (2) **the** modern world and became (3) **a** UNESCO Heritage Site in 1987. It is (4) **also** one of (5) **the** longest (6,700 km) structures in (6) **the** world, and has (7) **a** history of more than (8) **two** thousand years.

The building of (10) **the** wall began between (11) **the** 7th and 8th centuries BC as (12) **a** means of defending most of (13) **the** territory of (14) **China** from (15) **the** invading people of (16) **the** north. (17) **The** rulers of different parts of (18) **the** country built sections of the wall, and these were joined together in the time of (19) **the** Qin dynasty. During (20) **the** Ming dynasty (1368–1644 AD) (20) **the** wall was repaired and extended and took on the appearance it has today, with (21) **a** complex system of (22) **the** forts and towers. It has (23) **an** average height of ten metres and (24) **a** width of five metres, and it runs from (25) **the** east to (26) **the** west.