Born in Milan in the 1910s, brothers Achille and Pier Giacomo Castiglioni found their love of design early on. After graduating from Milan's famed Politecnico, the brothers joined the design studio of their eldest brother, Livio. Working on projects ranging from furniture and lighting to industrial and architectural design, they collaborated with Italian design giants like Gio Ponti and famed design houses like Alessi, Bernini and Zanotta.

Inspired by found items and curious shapes, the brothers wanted to create objects that were truly unique, not mass-produced. They designed minimalistic pieces elegant in their simplicity, with exquisite craftsmanship and surprising functionality in every detail.

The Castiglioni brothers had a great idea while walking through Paris in the early 1960s. Gazing upon the elegantly arched streetlamps of the city inspired an ingenious lighting design. They imagined a lamp that would provide light from above - but would also be portable, with a slim profile to allow people to walk around it. The result: the innovative Arco Floor Lamp, introduced by FLOS in 1962.

The lamp has an arch made of three steel sections nested one inside the other, making it possible to adjust the height of the lamp as desired. The stem extends to nearly eight feet in height. The steel dome diffuses light evenly and is also adjustable to change the angle of the light. It also has tiny holes on top to allow the bulb to cool.

Perhaps the biggest design innovation of the Arco Floor Lamp is the arch itself. In fact, Arco is the first arch-shaped lamp in the history of lighting design. To achieve this arch shape without the lamp falling over, it was necessary to design a heavy, yet moveable base.

The designers chose Carrera marble for its strength, weight and beauty. The slim base weighs in at 132 pounds. Always blending form with function, the Castiglionis designed beveled, bump-proof corners and created a hole in the base to make the lamp easier to move: Slipping a broomstick or rod through the hole allows two people to lift and relocate it with ease.

The lamp was an instant success, captivating designers and architects alike following its debut. It has received several awards, including the prestigious the Compasso d'Oro in 1979. It's also part of the permanent collections of Milan's Triennale Museum and MoMa in New York City. This pop culture icon is also featured in famous Hollywood films like The Italian Job (1969) and Diamonds Are Forever (1971). In response to the countless imitations, Arco was the first piece of industrial design to receive copyright protection in 2007 - just like a work of art.

FLOS has continuously produced the Arco Floor Lamp since its introduction. To mark the lamp's 60th birthday in 2022, FLOS released the Arco K - a limited edition design with a beautiful crystal base. This timeless treasure of midcentury modern design endures, celebrating the legacy of the visionary Castiglioni brothers.