Just two months after leaving the State Department, Hillary Clinton began a short but very lucrative speaking career to banks, securities firms, trade associations, and three times, Goldman Sachs.

In October 2013, Hillary Clinton was paid $225,000 to speak at Goldman Sachs "Builders and Innovators" conference, held at the Ritz Carlton Dove Mountain Resort in Marana, Arizona.

It was structured as a conversation between Clinton and Goldman Sachs CEO Lloyd Blankfein, according to two attendees. The audience was filled with tech entrepreneurs and investors.

One of the attendees CNN spoke to said that Clinton was friendly with Blankfein, but not overly so.

"There was definitely a familiarity with Lloyd," the source told CNN. Clinton was "certainly was not critical of banks. There was nothing that made the audience uncomfortable, and there were many people from Goldman in the audience. It was one smart person talking to another smart person about global macroeconomics."

CNN found many tweets about the event that day, including quotes about Tesla founder Elon Musk, who was also a speaker. But there was nothing on Twitter about Clinton. Why not? "It could have been that she was boring," said the source.

The second source who attended the same conference had the same recollection: Nothing Clinton said was controversial or memorable.

Clinton's speaking engagements have become center stage in her primary battle for the Democratic presidential nomination with Bernie Sanders. Sanders has challenged Clinton's coziness with Wall Street, especially taking in millions in campaign donations from bankers and Wall Street investors.

The speech in 2013 was one of three Clinton made on behalf of Goldman Sachs. According to public records, Clinton gave 92 speeches between 2013 and 2015. Her standard fee is $225,000, and she collected $21.6 million dollars in just under two years. Clinton made 8 speeches to big banks, netting $1.8 million, according to a CNN analysis.

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There is nothing illegal or unethical about former Secretaries of State earning money on the speaking circuit. And according to sources in the industry, there is nothing unusual about someone with the name value of Hillary Clinton being able to charge so much.

The standard fee and her demands are outlined in a memo from the Harry Walker Agency in New York.

According to the memo, Clinton requires travel by private jet, and even specifies that she prefers a Gulfstream 450 or larger. Her staff requires first class and business class tickets. And two members of her staff require up to three days on site to prepare, with all local transportation and meals included.

The memo states Clinton should be booked into a presidential suite with up to three separate rooms attached.

Clinton also requires a flat fee of $1,000 to pay for an onsite stenographer to record everything she says. However, Clinton is not required to provide the host with a copy, according to the memo.

Costs associated with her demands are on top of her speaking fee.

The speeches have been shrouded in privacy. Her staff has limited photographs and at times even confiscated cell phones. Attendees of some Clinton speeches complained vocally on social media that they were told to turn their phones off -- no photos, no live tweeting.

In the summer of 2013, Clinton spoke before a major convention of human resources executives. The group had previously hosted speeches of Colin Powell and Condoleezza Rice, both former Secretaries of State. John Hollon, an editor for an online trade journal attended both, and tried to attend Clinton's speech. He says he was kicked out due to Clinton's request for no media.

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"This is the only time in 10 or 11 years of going to to the annual event, which is the biggest human resource event of the year, the only time they have banned press from any speaker," said Hollon.

There was no reason given, he says. The Society for Human Resource Management, the host of the event, told CNN: "All keynote speakers come with some requirements."