If Don Draper were going to drink Old Fashioneds in Tokyo, he would definitely drink them in the Orchid Bar of the Hotel Okura. Wood-paneled with lighting as dim as midnight, and smoked-glass ashtrays lined up along the counter, the bar looks like something straight from the set of “Mad Men.”

To get to the bar, he’d have to walk through the defiantly retro lobby, with its olive green carpet and modernist chairs, geometric leaf pattern latticework and stylish “cut gem” pendant lamps.

But the bar, and the main wing of the hotel, renowned among design buffs as the perfect combination of Japanese aesthetics and modernist decor, will be bulldozed this summer, the latest victim of this country’s “tear-down” culture.

The demolition of the Okura also will rob the American Embassy, which is across the street, of a hotel that has been serving as a de facto boarding house and canteen for visiting Americans for decades. So integral is it to the embassy’s operations that diplomats refer to it as “the annex.”

U.S. presidents — including Richard M. Nixon, Gerald R. Ford, Jimmy Carter, Ronald Reagan, George H.W. Bush and Bill Clinton — have been hosted there. When President Obama was in Tokyo last year, where did he stay? At the Okura, of course.

Visit on any day of the week and you can expect to run into an assistant secretary eating the famed French toast in the Orchid Room breakfast restaurant or a special adviser drinking beer in the Orchid Bar.

But the American guest list is not limited to politicians and bureaucrats. Madonna, Michael Jackson and Harrison Ford have stayed there, too.

While Don Draper may not have visited, another fictional ­lady-killer did: When James Bond arrived in Tokyo in the 1964 Ian Fleming novel “You Only Live Twice,” he went straight to the Okura.

Come August, the Okura of lore will disappear.

The main wing of the hotel, home to the landmark lobby and renowned meeting places, will be pulled down and a $1 billion, ­3 1/2 -year construction project will begin, resulting in two glass towers — one for a five-star hotel, the other for a six-star — being built in time for the 2020 Tokyo Summer Olympic Games. The south wing, on the next block, will remain open during construction.

The history of the Okura, built on a site where samurai lived in the Edo period, in many ways echoes the history of modern Japan.

It opened in 1962, in time for the 1964 Tokyo Summer Olympics. That landmark event marked Japan’s revival and return to the international stage following the ignominy of World War II, and it resulted in the construction of other modernist gems, such as the Yoyogi National Gymnasium, with its sweeping roof, and the Nippon Budokan martial arts arena.

The hotel was designed by Yoshiro Taniguchi and Hideo Kosaka, who combined modernist design with traditional Japanese colors and patterns such as the hishi diamond, used in motifs throughout the hotel. Everything was done with the Japanese spirit of “wa,” or harmony, in mind. The chairs and tables in the lobby are spaced to look like five-petaled plum blossoms.

Hiroshi Matsukuma, a professor at Kyoto Institute of Technology and head of Docomomo Japan, a group that tries to safeguard modernist architecture, said the Okura symbolized Japan’s return to international society after the war.

“It was a collaborative work with Japanese traditional aesthetic, artisans’ handwork and the highest-class art made by living national-treasure artists,” Matsukuma said. “You can sense how high people’s aspirations were at that time. The main lobby speaks for itself.”

But with its rooms stuck in 1960s dimensions and only slightly more-recent decor, the Okura has been struggling to hold its own against increasing competition from foreign rivals.

“The facilities are getting old. This hotel was built 53 years ago,” Masaki Ikeda, president of the Okura, said in an interview in one of the hotel’s suites, currently on a “see it while it lasts” special at $4,000 a night (not including tax).

The plumbing is old and the building is not up to the latest earthquake standards, Ikeda said. Some buildings, such as the Kagawa Prefectural Gym designed by renowned architect Kenzo Tange, have had to be closed because the cost of making them compliant with modern earthquake regulations was prohibitive.

“We are going to create something that is even more aesthetically pleasing,” Ikeda said. The main architect for the redesign is Taniguchi’s son.

Still, design enthusiasts have mounted campaigns to stop the Okura’s demolition.

Tomas Maier, creative director of Bottega Veneta, an Italian luxury label, has said it is “crucial to make sure these great buildings are preserved” to pass down Japan’s modernist heritage to future generations. The company has started a #MyMomentAtOkura movement on social media, asking people to share their experiences at the hotel.

Monocle, a design magazine, is running a “Save the Okura” petition.

“Change and construction are features of life in Tokyo and contribute to the city’s thrilling sense of purpose and energy,” the petition reads. “But should they come at the expense of the capital’s history and identity? The greatest world cities — Tokyo among them — are the ones that are rich in texture.”

The Okura’s management reports a steady stream of letters and e-mails pleading for the building to be spared. It has been receiving many inquiries about the furnishings — the lobby lanterns in particular — but has not decided what to do with them.

Japan’s tear-down culture is partly the result of its history of devastating earthquakes and World War II bombing campaigns, neither of which gave the nation any say in the destruction.

But there also could be an inherently Japanese aspect at play. Japan’s renowned Ise Shrine is torn down every 20 years, and an exact replica is built right beside it. This echoes the Shinto belief in the constant death and renewal of all things in nature.

During Japan’s rapid ascent into the ranks of the world’s top economies, bulldozing and building from scratch became the norm, said Hiroyasu Fujioka, professor of architectural history at Tokyo Institute of Technology and an expert on Taniguchi’s architecture. Even now, despite Japan being in its fourth recession in six years, the capital’s skyline is a jumble of cranes.

“Right now, Japan operates as a capitalist society and development is the top priority,” Fujioka said. “Architecture is treated like a commodity and land is just considered a product, so what’s on that land is easily demolished.”

Matsukuma, the champion of Japanese modernism, considers the impending demolition of the Okura emblematic of broader problems in Japan.

“We should think more fondly about architecture and think what’s important to us,” he said. “What will Tokyo look like in 50 years? Our population is declining. The city might be full of empty buildings.”

Yuki Oda contributed to this report.