Based on the clue 'by the age of 10 this 21 young man had already vis...', what is the answer?

Based on the clue 'by the 400s bc the greeks had perfected 3 orders o...', what is the answer? Based on the clue 'by the 4th century ad rome had 28 public ones stac...', what is the answer? Based on the clue 'by the 6th century this group had joined with the ...', what is the answer? Based on the clue 'by the 7th century this civilzations city of tikal...', what is the answer? Based on the clue 'by the age of 5 this 18th century child prodigy kn...', what is the answer? Based on the clue 'by the british term this would be fun fair cruise ...', what is the answer? What is associated with: by the dawns early light of sept 14 1814 the us flag was still flying over this baltimore fort? What is associated with: by the end of 1845 mormon industry had turned it from swampland into the largest city in illin…