The land has been prestigious for centuries. During the Edo period, it served as the residence of the Sakakibara family of the Echigo Takada clan, then passed to the Makino family of the Maizuru clan in the early Meiji era. When Hisaya Iwasaki acquired the property in 1896, he was twenty-eight years old and had just returned from the United States, where he had earned a degree from the University of Pennsylvania. He had been Mitsubishi's third president for three years, having inherited the role from his uncle Yanosuke. His father, Yataro Iwasaki, had founded the Mitsubishi empire from a single shipping company in the 1870s. Hisaya wanted a residence that reflected both his Western education and his Japanese heritage -- a home that could function as a diplomatic stage while still honoring the traditions of the land it stood on.

To design the Western mansion, Hisaya hired Josiah Conder, the English architect who had arrived in Tokyo in 1877 and become known as the father of Japanese modern architecture. Conder's two-story wooden residence draws on the Jacobean style of 17th-century England, but threads in Islamic motifs from the Renaissance and a second-floor colonnade modeled on the Ionic order of a Pennsylvania country house -- a direct nod to Hisaya's alma mater. The south side features a veranda with colonnades that would not look out of place in Philadelphia's Main Line suburbs. Inside, the walls are covered in Kinkarakami, a Japanese wallpaper technique that presses metal foil through wooden rollers and hammers it with brushes to create a surface resembling colored leather. The technique, developed in Japan, was exported to Europe and became fashionable there before circling back to decorate this peculiar Anglo-Japanese hybrid. It is a building where East and West do not so much blend as argue productively.

A short walk from the main residence -- or an underground passageway, if you prefer -- stands the billiards house. Conder designed it to resemble a Swiss mountain chalet, a style almost nonexistent in Japan. The all-wood structure features log walls, carved pillars, and protruding eaves with Gothic flourishes. It is an eccentric building, clearly designed for leisure and display rather than any pretense of fitting into its Tokyo surroundings. The Japanese-style residence, meanwhile, was integrated directly with the Western mansion. At the time of completion, its floor space reached 1,815 square meters, rivaling the Western wing in sheer size. The interiors held painted screens and fusuma sliding doors by Hashimoto Gaho, one of the leading painters of the Meiji period. Originally, the Japanese section comprised seven distinct buildings and was considerably larger than its Western counterpart -- a reminder that for all the imported grandeur, the Iwasaki family still lived primarily in Japanese style.

After World War II, the estate was confiscated by the Supreme Commander of the Allied Powers. When it was returned, the Japanese government repurposed it as the Judicial Research and Training Institute of the Supreme Court, a function it served until 1970. The Department of Justice demolished nearly all of the Japanese-style buildings during this period, reducing the property to less than half its original size. The garden, once elaborate, was stripped down to little more than a lawn, though stone lanterns, monuments, and a hand-washing basin survive from the Edo era. What saved the remaining structures was a 1961 designation as an Important Cultural Property, extended to the entire property in 1999. Since 2001, the Tokyo metropolitan government has administered the site, and the approximately 17,000-square-meter grounds are now open to the public. The mansion, the chalet, and one Japanese building stand as the surviving fragments of a twenty-building estate -- a fraction that still manages to tell the whole story of Meiji-era Japan's extraordinary experiment in cultural fusion.