Possible Clues:

• Hasten (anag) — capital city
• Brief answer to secure the capital
• Capital invested in exotica, then squandered
• Destination of the first marathon (490 B.C.)
• Home of Demosthenes
• After Paris (1924) and London (1948), the third European city to host the summer Olympics for a second time
• Capital of Greece ... and when parsed differently, a hint to the starred clues' answers
• Parthenon location
• Hellenic capital
• Capital at that time invested in cash essentially