The Silk Road marketplace went online on January 27, 2011, created by Ross Ulbricht under the pseudonym "Dread Pirate Roberts." A proof of concept for Bitcoin’s independence, censorship resistance, and pseudonymity, Silk Road was the first modern darknet market -- an online marketplace accessible only via Tor that used Bitcoin as its sole currency. While controversial, it demonstrated that Bitcoin could function as permissionless money beyond the reach of any government. By the time the FBI shut it down in October 2013, Silk Road had processed over 9.5 million BTC in transactions.
Wikipedia: Silk Road