Christie’s has announced that it will offer eleven works from Cy Twombly’s personal collection during its upcoming sale of Post-War and Contemporary Art in New York. The works, which are being offered by the Cy Twombly Foundation,  were all created between 1961 and 1967 by artists represented by the legendary Leo Castelli Gallery -- Twombly’s dealer for over four decades. The collection is expected to fetch around $15 million.

Twombly, who is best known for his calligraphic, graffiti-like paintings, collected works by his friends and contemporaries, including Roy Lichtenstein, Andy Warhol, Bruce Nauman, and Claes Oldenburg.