The tour bus was full, and the 50 men, women and children were settling into their cushy, air-conditioned confines when Anthony T. Browder offered a gentle reminder: "This is a field trip, not a tour. We can't afford to be tourists. This is a learning experience."

Learning requires attentiveness, questions and a little note-taking -- all of which occurred during three hours of riding and walking around Washington, stopping on occasion for lectures, leaning down and then standing on tiptoe to get a better view. Most were sweating under the blazing sun during the portion of the trip that involved climbing stairs.

Browder's lesson, the one he's been pushing for 18 years, is that Washington -- a city of secrets, political and personal -- has hidden its biggest secrets in plain sight. Look around, he said, and it's clear to the trained observer that symbols and mythologies hatched thousands of years ago on the banks of the Nile River influenced the layout and design of this capital city.

That most people don't know that, he argues, is part of a deliberate effort to obscure the contributions of black people to America -- something that began as soon as slaves arrived and continues today. His goal for black Americans, in particular, is to understand that what they were taught is not necessarily the whole truth, and that unearthing reality requires vigilance and hard work.

"We were written out of history," said Browder, author of "Egypt on the Potomac." "Tourists leave this city wondering what is wrong with black folks, never knowing the role that we've played in the creation of this great city. We have to tell our story."

One of the stories he tells is about Benjamin Banneker, a black man who was part of the team that conducted the survey for the city before it was built. But Banneker gets less credit than Pierre Charles L'Enfant, who quit the project and was bailed out by Banneker, said Browder. L'Enfant has a plaza named for him, Banneker a tiny park nearby.

"How many of you were taught that?" Browder asked on a recent trip. "How much more have you not been taught?"

Browder's tours grew from his studies and travels. An author and lecturer, Browder became interested in Egyptian history after graduating from Howard University. His knowledge is drawn from 39 trips to Egypt over the last two decades, including one this summer in which he led 210 people on an excursion to study and learn through his Institute for Karmic Guidance, on H Street NE.

Like many in Washington, he aims to push people toward action. He presses them to ask questions and challenge him. And they do. One question he gets often is why, in his literature and on tours, he refers to Meridian Hill Park instead of Malcolm X Park, as many people call it. He has a ready answer.

"The park doesn't deserve the name," he said. In the 1970s, when black people began calling the park after the assassinated black activist, they did not organize to keep it clean, and they allowed prostitutes and trash to proliferate, he said. Browder wants less complaining about the displacement surrounding gentrification and more work to stop it from occurring. He switches easily between current events and ancient history, believing that it's important to use the past as a guidepost for the future.

For him, much of that past leads to Africa, and what he calls the fascination of the founders and designers of the city with ideas first used in Africa: the laying of the cornerstone at new buildings and the repetition in local architecture of Egyptian pyramids.

The similarities are striking, he said, pointing to the Washington Monument, a tribute to America's first president, as a prime example. It's a copy of a 6,000-year-old memorial that honored the resurrection of Ausar, an African god. And the Masonic temples along 16th Street NW -- the Scottish Rite Temple in the 2800 block and the House of the Temple in the 1700 block -- are modeled after those in ancient Egypt, or Kemet, the country's original name. Ancient influences, and replicas of pyramids and obelisks, can be seen all over the Mall, he said.

The Masonic temples and their prominence on 16th Street, Browder said, are examples of the founders' belief in the principles of freemasonry, which has its foundation in Africa. But the links to Africa are often obscured. Browder said that when the Greeks changed the name of the country now known as Egypt along with the names of prominent symbols -- tekhens, for example, became obelisks -- the original meanings of the symbols were altered.

Acklyn Lynch, an activist scholar and retired professor of Afro American studies, held a tape recorder to capture the trip so he could listen to it again.

"It shows that the founders were aware of African historiography," he said. "The question for me is, what is the relationship of this to gentrification? How can we get this information out before black people have left the city? . . . If you know you are essential, and have been essential, then your desire to live in the city is different."

Sam Paige of Upper Marlboro met Browder while fixing the phone lines at the Institute for Karmic Guidance. The two clicked and Paige went on a tour.

He liked it so much that he brought 40 members of his family, selling out an entire bus with siblings, nieces, nephews and friends.

"I wanted to enlighten my family," he said. "When we know what we've done, we know what we're capable of."

That's the kind of response Browder seeks: for black people to understand that their ancestors provided this country with much more than labor.

"Our story does not begin in slavery, but thousands of years earlier," he told the people on the bus. "The nation's founding fathers incorporated African culture into the capital of the world's most rich and powerful nation. If it was good enough for them, it should be good enough for you. . . .

"Dates and names and numbers don't mean anything if you don't find a practical application for it in your life," he said.

Browder is so confident in his information that he offers to refund the $20 cost if people can't see how the story he tells is relevant. He had no takers after a recent tour.

"It opens my mind," said Tamara Wade, 25, who teaches at Lake Arbor Elementary in Prince George's County. "It makes you want to find out more and share it with others."

"This is a field trip, not a tour. We can't afford to be tourists. This is a learning experience," says Anthony Browder, leading a group that will delve into Egyptian influence in the District. A group watches a video on the bus during Anthony Browder's three-hour "Egypt on the Potomac" trip. The Washington Monument, above, is a copy of an obelisk built by Africans in honor of the god Ausar, Browder says. Egyptian pyramids, such as those adorning the Arthur M. Sackler Gallery, left, are part of the symbolism in the capital city's architecture. "Our story does not begin in slavery," Anthony Browder tells tour groups, "but thousands of years earlier."