Paul Signat's 'Quai de Clichy,' found in Gurlitt hoard, returned to family of Gaston Prosper Levy, who fled from Nazis in France

Ownership of art piece can apparently only be traced back to 1970s; Cairo wants representation of infamous pharaoh's returned to its country of origin

Foreign Minister Heiko Maas to travel to Florence where he will hand over 'Vase of Flowers' by Dutch artist Jan van Huysum to Uffizi Gallery

Thousands of artifacts plundered by Nazis still held in French museums; government vows 'active role' to find owners