The Shinjuku Sumitomo Building (新宿住友ビル), nicknamed the Sankaku Biru [三角ビル, Triangle Building], is a pioneering skyscraper in Tokyo’s Nishi-Shinjuku business district. Completed in 1974, it was Japan’s first building to exceed 200 meters, reaching 210 meters with 52 floors. Its bold triangular footprint and sharp lines offered a stark contrast to the boxy towers of its time, establishing it as a futuristic icon in Tokyo’s rapidly verticalizing skyline.

At its core is one of the building’s most extraordinary features: a soaring triangular atrium that extends from the ground floor to the roof without interruption. This central void, rarely seen in high-rise architecture, evokes a cavernous sense of space and light. The geometric purity of the triangle is echoed throughout—from the sharp angles of the ceilings to the symmetrical alignment of walkways and beams—creating a unified architectural experience. Entering the lobby, visitors often liken the atmosphere to a sci-fi cathedral or space station, underscoring its imaginative impact.

As part of a major renovation completed in the 2020s, the building introduced Sankaku Hiroba [三角広場, Triangle Plaza], a massive, glass-roofed event space that reinforces the building’s public-facing mission. Measuring 140 meters long and 25 meters high, the plaza is column-free at its center, making it an ideal venue for exhibitions, pop-up markets, and performances. Beyond its cultural role, it also functions as a disaster response facility, capable of sheltering nearly 3,000 people—underscoring Tokyo’s blend of innovation with preparedness.

The complex offers more than just architectural intrigue. From the basement to the second floor, visitors can explore a well-curated selection of 26 shops and eateries, along with notable facilities like the Asahi Culture Center, which hosts workshops and lectures, and the Peace Prayer Exhibition Museum, a quiet space dedicated to reflection. On the upper levels, restaurants on the 48th to 52nd floors offer panoramic views of Tokyo, making it a serene retreat above the urban sprawl.

For photographers and architecture enthusiasts, the building is a visual playground. The atrium's verticality, filtered sunlight, and glass-and-metal detailing create opportunities for dynamic compositions, especially when shot with wide-angle lenses from low or high vantage points. The glass ceiling above Sankaku Hiroba also allows for atmospheric interior shots on rainy days. Exterior captures are best during golden hour when the triangle-shaped tower casts dramatic shadows against the Shinjuku skyline.

Blending historical significance with forward-thinking design, the Shinjuku Sumitomo Building remains a cornerstone of Tokyo’s urban evolution. Its triangular vision, from atrium to plaza, symbolizes the city’s embrace of form, function, and public spirit—offering both a space to admire and one to gather.