What was known as "seward's folly"?

The Treaty with Russia was negotiated and signed by Secretary of State William Seward and Russian Minister to the United States Edouard de Stoeckl. Critics of the deal to purchase Alaskacalled it "Seward's Folly" or "Seward's Icebox." Opposition to the purchase of Alaska subsided with the Klondike Gold Strike in 1896.