Oswald Haerdtl was a prominent Austrian architect, designer, and teacher, active during the first half of the 20th century. He is best known for his furniture designs, which are characterized by their simple, functional forms, and a focus on craftsmanship and materiality.

One of Haerdtl's most famous designs is the chair known as No. 515, which he created in 1955. The chair is a classic example of Haerdtl's approach to design, featuring a sleek, minimalist form that emphasizes the beauty of the materials used.

The chair is made from solid beech wood, with a seat and backrest that are formed from a single piece of molded plywood. The legs of the chair are angled slightly outward, providing stability and a sense of visual balance.

The No. 515 chair has become an iconic piece of Austrian design, prized for its simplicity, elegance, and durability. It has been used in a variety of contexts, from private homes to public spaces, and has become a symbol of the country's rich design heritage.

In addition to his furniture designs, Haerdtl was also known for his work in architecture, particularly in the design of modernist buildings that blended functionality with aesthetic beauty. His legacy continues to influence designers and architects to this day.