It is hard to miss the Everett House, just off Dupont Circle, in the heart of the great avenues of Washington DC’s Northwest district. The mansion, formerly the Turkish embassy in the United States, and today the ambassador’s residence, gleams resplendently – easily surpassing the other late-19th-century wedding cakes that surround it. Like Hearst Castle in San Simeon or Citizen Kane’s fictitious Xanadu, this is imperial American architecture of the Gilded Age: haphazardly filled with priceless porcelain, paintings and murals; fireplaces big enough to live in; and an eclecticism that flagrantly mixes styles, periods and motifs – all washed down with indecent quantities of gold leaf.

The man who built the mansion, Edward Hamlin Everett, was a mogul from Cleveland, Ohio who had invented the bottle top, earning the nickname “the Bottle-Top King”. This was the era of American oligarchs: the newspaper magnate William Randolph Hearst was setting the get-rich-quick tone of the age, and oil and rail barons such as the Vanderbilts were rapidly dominating both politics and high society. From the Gilded Age, chronicled so acerbically by Edith Wharton and Henry James, come the great mansions of the USA, such as Biltmore in South Carolina, and the great summer “cottages” of Newport, Rhode Island, which herald a new scale of architecture among the ruling class. Like those of his rivals, Edward Hamlin Everett’s Washington palace was a place to display his new-found wealth and power. The mansion became a social and political statement made all the more weighty by its overwrought architecture.

His chosen architect, George Oakley Totten Jr, was a graduate of the Paris École des Beaux-Arts and, like many from that school, a master of the eclecticism popular in the first decade of the 20th century. Uniquely, however, he had spent time in Istanbul, in the employ of both the sultan and the grand vizier. Totten had travelled to the Ottoman Empire in 1908 to construct the chancery of the American embassy – an annexe to the Palazzo Corpi that is still visible today. While there he was commissioned to build a grand residence for Izzet Pasha, a prominent figure in the court of Sultan Abdülhamid II, later to be grand vizier. Abdülhamid himself then employed him as “Private Architect to the Sultan”, but before Totten could accede to this position, the sultan was ousted in the Young Turk Revolution of 1909. Returning to Washington DC, Totten quickly became the darling of those seeking statement architecture in the city’s fashionable Northwest. The Bottle-Top King approached him with a simple brief: “Spend and dream”. “Cost is no object,” he said, “and the style and design are up to you.”

The resulting edifice, erected on the site of a former city dump, exemplifies Totten’s peculiar genius for eclecticism. As one critic remarked, “Totten designed spaces as individually and stylistically unrelated to the exterior as they were to each other.” The effect is garishly sumptuous. As one moves past the Neoclassical façade, rooms jump from Baroque to Ottoman to Renaissance to Art Nouveau styles, studiously maintaining their individual integrity against each other. “There is something more to architectural style than mere decorative detail. This point George Oakley Totten often failed to understand,” sniffed another critic. Certainly, compared with that of his contemporary, Frank Lloyd Wright, Totten’s work seems shockingly anachronistic.

Yet such criticisms are beside the point. What Everett sought was a house that would display his wealth to guests and his power to those who came to broker deals with him. After its completion in 1915, the building rapidly acquired the nickname “San Simeon on the Potomac”, a reference to Hearst’s castle in California, where film stars and politicians frolicked in gardens filled with zebras and halls stuffed with priceless art bought in bulk. In Washington, Everett became famous for his lavish musical parties, at which he and his wife, the opera singer Grace Burnap, would sit on matching Art Nouveau chairs. The house was stuffed with lavish acquisitions, including two Bronzino paintings that hang casually in the stairwell and a unique collection of Sèvres porcelain. Totten’s other buildings in the city – the Pink Palace, the Hague House (now the Cameroonian embassy), the Moran House (now the Pakistani embassy) – would all act as stages for the extravagant social parties and fervid political machinations that defined turn-of-the-century Washington. This world would not last. The Great Depression brought an end to the glamorous social circuit, and the great palaces of the magnates became embassies, ambassadorial residences and consulates.

After the death of Edward H Everett, his much younger widow, Grace Burnap, approached the Turkish government with the offer of renting out the mansion. The ambassador from Turkey, Mehmet Münir Ertegün, moved in with his family in 1934. They would stay for the next ten years. The republic eventually bought the mansion, fully furnished with Everett’s antiques.

Arguably the Ertegün family exemplifies all the successes of Turkey in the 20th century. In the dying days of the Ottoman Empire, Mehmet Münir was an up-and-coming international lawyer working as an adviser to the sultan. With the War of Independence, however, he soon found himself playing a key role in Atatürk’s Ankara-based government. His diplomatic career took off following his posting as legal adviser to the Lausanne Conference. His first official position was as Turkish observer to the League of Nations in Geneva, followed by postings as ambassador to Paris and London before his appointment to Washington in 1934.

Ertegün’s daughter, Selma Göksel, who was born in Paris, remembers travelling to Turkey for the first time that year. The family summered in Heybeliada, one of the Princes Islands near Istanbul before boarding a ship for New York. “It was like heaven. You don’t need me to tell you how much it has changed,” she says. From there Ertegün, his wife, Hayrünisa, 11-year-old Ahmet and nine-year-old Selma travelled down to the capital. Nesuhi, their elder son, had stayed in Paris, getting to know the jazz music that filled the city.

“On our drive through Washington to the embassy, the consul-general played a game with us,” Selma Hanım remembers. “As we drove through the rougher neighbourhoods, he would point to the most dilapidated building he could see and say, ‘That’s the embassy!’ and laugh when he saw Ahmet and me looking dejected. So when we arrived at the real thing we couldn’t believe our eyes. We ran though the rooms, shouting and laughing. None of the previous embassies had been this beautiful or this big… Size is very important when you’re a child.”

Ertegün was a quiet, sober, devout man who “would sit in his office and drink his tea in a bowl” – the Uzbek way (his mother had been Central Asian in origin). His melancholy is still almost palpable. The family’s summer in Heybeliada in 1934 was their last view of the country until after the war, and Ertegün was never to see Turkey again, as he died before the war ended. Filled with homesickness for the country he represented yet could not see, he would stand for hours at the edge of the balcony, looking east, across the roofs of Washington and Chesapeake Bay towards Europe, towards Turkey.

Hayrünisa Ertegün, with her blonde hair and imposing manner, was more outgoing. She became a social linchpin of Washington society, so much so that on her return to the capital in the 1960s she was fêted, and her visit was written up in all the society columns. Ahmet’s naughtiness was legendary. “Once, in Switzerland, our mother was interviewing a new nanny,” Selma Hanım, herself a modest, self-effacing figure, recalls. “Ahmet leant over to me and said, ‘I don’t like her. Watch me!’ and crawled over to her and began to slice away at her skirt with a pair of scissors.” Needless to say, the nanny didn’t stay.

The Ertegün family shared a fondness for ping-pong, which they played in the ballroom. “We were all excellent at it, except for Nesuhi.” More significantly, they had music in their blood and carried on the tradition of musical parties started by Everett and his operatic wife. Hayrünisa was herself a great singer, and the family would often cluster round the grand piano in the ballroom. During Ahmet’s adolescence, the Bottle-Top Mansion gained its reputation for noise. Under the influence of his elder brother, Ahmet was soon inviting black jazz musicians to come and jam in his bedroom. “In summer we would throw all the windows open because of the heat,” says Selma Hanım, “and the Romanian embassy across the road would complain.”

The commotion these sessions caused was about more than just the noise, however. “You see, Washington in those days was segregated – like a Southern city. And in the grand houses of a Southern city, black people didn’t come in the front door. In fact my father received a letter from a senator informing us that in Washington DC black people use the back door. My father replied, simply: ‘In our country our friends enter through the front door. If you should ever come to visit us, you can feel free to use the back door.’”

Selma Hanım is still full of stories that illustrate life in the Washington of the Thirties and Forties. In the winter of 1941 her mother arranged for her coming out as a Washington debutante at the embassy. A dress was made, invitations sent. But the declaration of war on December 11 meant that the party had to be cancelled, much to the young girl’s dismay. Selma’s best friend at school, Anne Curzon-Howe, was set to travel back to Britain, despite the danger such a trip would entail. At school assembly they “sang the sailor’s hymn For Those in Peril on the Sea. Anne reached for my hand and squeezed it and I could tell how terrified she was”.

Mehmet Münir Ertegün is considered an important force in advocating Turkey’s neutrality during the war, but his role as the country’s representative was a hard one. When he suffered a heart attack on the morning of October 29, 1944, there was no question but that he should attend the Republic Day reception at the embassy that evening. “He shook hands for two hours before going back to bed. He never recovered, and died two weeks later, on November 11.”

The body of Mehmet Münir Ertegün was interred in Arlington Cemetery until after the war, when it was taken back to Turkey with great fanfare on the USS Missouri – a grand gesture about which Selma Hanım has no illusions. “Of course it was a great honour, but it was a political move. The Cold War was starting and we [Turkey] were more important than ever.” Selma and her mother returned to Turkey with the body; Selma was to marry and settle in Ankara. The Ertegün brothers, meanwhile, eschewed diplomatic careers and proceeded to define the sound of popular music, famously bringing black music to white audiences. Ahmet founded the enormously influential Atlantic Records in 1947; Nesuhi joined him a few years later.

The arrival of Faruk and Mevhibe Loğoğlu at the embassy in 2001 would begin the latest phase in the history of the building. The fun-loving, larger-than-life “Mimi” Loğoğlu was famed for her sense of style and dinner parties that would culminate in guests dancing in the ballroom to songs by the pop singer Tarkan. Of all the yearly benefit evenings held at embassies throughout Washington, Mevhibe Loğoğlu says, “We had the highest-priced tickets – because of the building and because of the food!” Yet by this time the mansion was falling apart, with the back of the building subsiding into Rock Creek Park. The Loğoğlus made the decision that a full refurbishment was necessary, which meant relocating to a new, smaller home. “You need space for entertaining… It was a difficult sacrifice.”

Mevhibe Loğoğlu took a personal interest in the $20 million restoration, working closely with the interior designer and arriving at the building site every week to inspect progress, dressed head to toe in Turkish designers such as Gönül Paksoy. “I made them keep the swimming pool in the basement. It was being used to store the embassy’s archives and they wanted to do away with it, but I made them keep it just the way it was.” As the refurbishment continued, astonishing things emerged from the attic, including an enormous Aubusson carpet valued at $1 million but in desperate need of repair. Such items bear small witness to the extreme luxury of the Everett House, “the pearl of Turkey’s residences”, in Mrs Loğoğlu’s words.

The refurbishment, begun by the Loğoğlus and finished by their successors, the Şensoys, in 2009, has restored the integrity of the sumptuous mansion George Oakley Totten plucked from Edward Hamlin Everett’s dreams and set down on a city dump. From the unique Sèvres porcelain to the painstakingly restored Gobelin wall tapestries, today the building shines in a way it hasn’t since its heyday.