Datebook: 5.11.09

Five things worth knowing today - HBO continues its sad but necessary Alzheimer's Project tonight, a collection of documentaries devoted to the suffering, science, and future of this debilitating disease. - Architect Frank Gehry and composer/conductor Esa-Pekka Salonen come to the New York Public Library for a discussion of their life and work. - Meanwhile, libraries in L.A. are hopping too: on the West Coast, Steve Martin plays the banjo and chats with Dave Barry to benefit the Los Angeles Public Library. We'd say this, in a nutshell, is the difference between New York and L.A. - Today in 1924, Gottlieb Daimler and Karl Benz merged their two companies to form Mercedes-Benz. - And today in 1978, French supermodel Laetitia Casta was born. That minor miracle ought to be enough to get you at least to Tuesday. The many reasons why, below. MATTHEW SCHNEIER