Most Impressive Defensive Walls?

Jan 2018
1,609
China (Hong Kong SAR)
#1
Which do you think are the most impressive walls for any castles or cities? So this would exclude the Great Wall as well as Hadrian's Wall, for example.

I propose this for consideration, the Ming city walls of Peking:


 
Jan 2018
1,609
China (Hong Kong SAR)
#2
Jun 2012
5,707
Texas
#4
-The defense in depth at Kursk, probably the strongest ever built.
-Defenses at Constantinople.
-Castle Gresyskull!
-The mountain NORAD is in. Slings and catapults aint nothing to protecting against nukes.
 
Jan 2018
1,609
China (Hong Kong SAR)
#7
"The fort is 1,500 ft (460 m) long and 750 ft (230 m) wide and is built on a hill that raises above a height of 250 ft (76 m) above the surrounding countryside. The base of the fort has a 15 ft (4.6 m) tall wall forming the fort's outermost ring, within its triple ringed defence architecture. The fort's upper bastions or towers form a defensive inner-wall perimeter that is about 2.5 mi (4.0 km) long. The fort now incorporates 99 bastions, of which 92 were built or substantially rebuilt between the period of 1633-47. The fort also has four fortified entrances or gates from the townside, one of which was once guarded by cannon.[12]"
https://en.wikipedia.org/wiki/Jaisalmer_Fort

Doesn't detail the thickness though.