Hillary Clinton is stepping down as the top US diplomat firm in the belief she has restored America's global standing during her tenure that may also have traced a path to the White House in2016.

But as she sweeps out of the imposing buildings of the State Department for the last time, how will history judge her as secretary of state?

How she stacks up against giants of American diplomacy like Henry Kissinger and James Baker and how she'll fill in the blank pages as she opens a new chapter in her life remain open questions.

She now leaves office with the highest popularity rating of any of President Barack Obama's cabinet members, imbued with the title of "rock star diplomat" and with many saying she'll be the Democratic Party's strongest hope in the next elections, despite her constant denials that she is planning to run.

Critics say Hillary cannotpointtoa signature issue achieved under her stewardship. The major challenges of the day — Syria, the new world order emerging from the Arab Spring, Iran's nuclear ambitions and the search for peace in the Middle East — she bequeaths to hersuccessor John Kerry.

Yet the Obama administration seized the opportunity to heap praise on her in opening upMyanmar. She helped the United States pivot its focus toward Asia and built a solid alliance in support of biting sanctions against Iran.

And she brought to Obama's administration her charisma, celebrity status and a willingness to travel, believing that even in this interconnected world, face-to-face meetings remain one of diplomacy's most important tools.

"Remember what we faced in January 2009: Two wars. An economy in freefall. Traditional alliances fraying. Our diplomatic standing damaged," she told the Council on Foreign Relations on Thursday.

Four years on, while the world "remains a dangerous and complicated place," much has changed, she argued, saying "we've revitalized American diplomacy and strengthened our alliances."

"As a long-term enduring legacy, I think I'd feel prouder about that than having invaded another Middle Eastern country, "she said.

Observers also point to Europe's renewed faith in America, after Hillary made 42 trips to the continent during her time in office.