On my way to work today, I was listening to Dan Carlin and he was describing these absolutely massive walls. The depth and length didn't shock me but the height seemed far fetched. Is this historical exaggeration? Where can I find more information on how they were constructed? Thanks!!
The easiest one to source would be the walls of Babylon:
Herodotus gave around 300 feet for the height of the walls, but people that came after him slowly revised it backwards. Most notably one of Alexander's historians, Clitarchus, gave the estimate of 75 feet tall.
http://www.globalsecurity.org/military/world/iraq/babylon-walls.htm
The good part is that we actually have excavations of Babylon to check this source, since the Germans started excavating ancient Babylon in the early 1900's. They found that the outer city walls from the time of Nebuchadnezzar (page 6 in the source) were 7 (23ft) and 7.8 (25.5ft) meters thick.
http://www.jstor.org/stable/3154531?seq=6#page_scan_tab_contents
I'm not going to math it out, but the ratios on that seem almost directly on point for what Clitarchus was stating. It is entirely possible that they were built taller than that but there's a point of diminishing returns on wall height.
For stupendously massive walls, the best place to look is China, especially during the Ming period. The walls of Xian are probably the best preserved; they're almost nine miles long, forty feet high, and fifty feet thick. Walls of this type were more or less impervious into the 20th century; even armed with industrial, high explosive artillery, the British of the 19th century considered the walls of Beijing indestructible.
for reference:
Xian City wall
http://www.honeymoonguide.com.au/Images/xian-city-wall.jpg
Beijing city wall
Do you remember which civilizations he was talking about? Or, if you don't, which episode?
Question related to OP's one :
Were the Mycenaean not able to build such walls or something close to these sizes ? If I remember correctly the ruins we found are huge, especially for the time period.
Follow-on question(s): How well would such enormous walls protect the Meeds Medes, Assyrians, Babylonians, etc? Were there weapons that could make a hole large enough for an army to get through? Or was the only viable tactic to starve the inhabitants?
