Keystone Dates

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Across
  1. 2. Time range for era 2
  2. 4. The Declaration of Independence
  3. 5. Ottomans conquer Constantinople and rename it Istanbul
  4. 6. Fall of Berlin Wall and end of Cold War
  5. 7. Time range for era 1 (imagine "circa" or "c" before the first date - you don't have to write it)
Down
  1. 1. Time range for era 3
  2. 2. World War II ends with America dropping atomic bomb
  3. 3. Beginning of World War I
  4. 4. Time range for era 4
  5. 8. Columbus sailed the Ocean Blue