For most passers-by, the embassies along Massachusetts Avenue Northwest are nothing more than representations of foreign governments.

But for Mark Ozer, the former mansions stand for much more.

In a recent lecture, Ozer delved into the histories of these grand structures. The subject is the focus of his new book “Massachusetts Avenue in the Gilded Age: Palaces and Privilege.”

“There are lots of stories behind these facades,” Ozer said, and he had no shortage of them.

Ozer is a former docent for the United States Capitol Historical Society and retired professor of neurology at Georgetown University. He said he has been interested in the history of Washington since moving to the District in 1964. His lecture was part of the United States Capitol Historical Society’s fall lecture series.

“I’ve returned to my first love, which was history,” said Ozer, who studied the subject at Harvard University as an undergraduate.

Though many of the mansions, which were built mostly in the late 1800s, have been torn down, Ozer showed that before they were places of diplomacy and clubs, they were home to only the most fashionable Washington residents.

Pierre Charles L’Enfant’s master plan for the District did not go past Florida Avenue to the north, Ozer said. Beyond that was essentially a dumping ground.

“To go north of H Street was really a big, big deal,” Ozer said.

By the 1880s, Washington had become a popular destination for the newly rich who were unable to break into the tight social hierarchies of Boston or New York City. At that time, the British Embassy was the social hierarchy’s zenith, so when it moved north to Connecticut Avenue and N Street, other embassies followed.

Social elites were not far behind, hoping their daughters could marry the available sons of European diplomats.

Ozer shared the stories behind several of the historic houses.

The building on Sheridan Circle that now houses the Egyptian embassy was designed by architect Glenn Brown. Brown was the American Institute of Architects’ secretary and was responsible for establishing the organization’s presence in Washington. That presence led to the creation of the McMillan Commission, which planned the layout of the National Mall.

But Ozer’s favorite story from his research was the tale of the feuding Medill sisters, the heiresses to the Chicago Tribune. They lived at Dupont Circle and “competed with each other in every way they could,” each trying to win control of the Tribune for their children, he said.

“The only thing they seemed to work together on was ruining their husbands,” he said; one husband divorced his wife, while the other went insane.

The era came to an end during World War II, when most of the families could not afford to maintain their elaborate homes. Some were torn down or fell into disrepair, while others were purchased by foreign governments to be used as embassies.

Ozer is the author of about a dozen history books. “Massachusetts Avenue in the Gilded Age” is available through History Press at most bookstores.