That's the problem with going too far using "money" or "GDP" - you can roughly compare the WWII 45% of GDP spent with today - https://www.davemanuel.com/us-defense-spending-history-milit... because even by WWII much was "financialized" in such a way that it appears on GDP (though things like victory gardens, barter, etc would explicitly NOT be included without effort - maybe they do this?).
As you get further and further into the past you have to start trying to measure it using human labor equivalents or similar. For example, what was the cost of a Great Pyramid? How does the cost change if you consider the theory that it was somewhat of a "make work" project to keep a mainly agricultural society employed during the "down months" and prevent starvation via centrally managed granaries?
As you get further and further into the past you have to start trying to measure it using human labor equivalents or similar. For example, what was the cost of a Great Pyramid? How does the cost change if you consider the theory that it was somewhat of a "make work" project to keep a mainly agricultural society employed during the "down months" and prevent starvation via centrally managed granaries?