London's Tate Modern unveiled a huge, spectacular abstract painting by acclaimed US artist Joan Mitchell on Thursday, part of one of the "most significant gifts" to the gallery in recent decades.

Museum employees view a painting by artist Joan Mitchell called Iva 1973, donated by Jorge M. and Darlene Perez, at the Tate Modern in London, Thursday, April 3, 2025. (AP Photo/Kirsty Wigglesworth) ...