Karl Weierstrass (1815-1897) was among the leading mathematical figure of the 19th century, a man who had a decisive influence on the way we view analysis today. The centrepiece of this book is the reproduction of a photo album given to Weierstrass in 1885 as a 70th birthday present. The album, which lay hidden in a Berlin museum for over 70 years, contains the portraits of more than 300 students, friends and colleagues from all over Europe, and forms an extraordinary document of the admiration and appreciation shown to him. In an accompanying text, Reinhard Bölling gives interesting details of Weierstrass' life, the lives of those involved in the preparations for his birthday celebrations, and the story of how the album came about.