In 1821, Greece declared its independence, and thus began the Greek Revolution, which would last until 1832. From 1453 until 1821, Greece was under the sovereign rule of the Ottoman Empire.
However, when the revolution began, their former rulers did not give Greece up without a fight. The Turks (residents of the Ottoman Empire) used the Parthenon of Athens' acropolis as a military stronghold, particularly for ammunition storage.
Much of the metal in the Parthenon is lead, the metal used for ammunition at this point in history because of its malleability. When the Turks began running out of ammunition, they decided they would melt down the lead from the Parthenon to make more.
The Greeks, fearing one of the most important landmarks in their entire country would be destroyed, actually offered to give the Turks the same amount of lead that was holding the Parthenon together if they agreed to leave it intact!