German Chancellor Angela Merkel said the Nobel Committee "acknowledges the idea of the European conciliation" and said the euro is more than a currency.
"We should not forget this -- in particular during these weeks and months, in which we are working to strengthen the euro."
"Six decades of peace in Europe: For those of us who live in the European Union, that's a long period of time," Merkel added. "It's merely the blink of an eye in the course of history, which is why we must never forget that we must again and again work, strain and strive for this peace, for democracy, for freedom."
Italians in Rome rallying Friday against government cuts to public education weighed in. One woman said the prize appears to be a "hope for the future."
Another woman said she was pleased but a bit surprised because the EU could have made stronger commitments to peace. And a man said the European economy is no longer "for the people."
"We are the economy that works in favor of the banks," he said.
This year's winner was picked from 231 different nominations -- 43 for organizations and the rest for individuals, the Nobel Committee said.
Last year's peace prize came as a surprise to many observers, split as it was among three women: Liberian President Ellen Johnson Sirleaf and grassroots activist Leymah Gbowee, and Yemeni media freedom campaigner Tawakkul Karman, a symbol of the Arab Spring.
Johnson Sirleaf is one of many heads of state to have received the prize, including four U.S. presidents: Theodore Roosevelt, Woodrow Wilson, Jimmy Carter and Barack Obama.
The Peace Prize is the fifth Nobel Prize to be awarded this week, preceded by honors in medicine, physics, chemistry and literature.
Other large organizations have won the Nobel Peace Prize, including the United Nations, Doctors Without Borders, U.N. peacekeeping forces, the U.N. atomic energy agency and the International Campaign to Ban Landmines.