The Day of Patrons and Philanthropists, also known as the Day of Patrons and Benefactors, is observed in Russia every April 13. This unofficial holiday was initiated by the State Hermitage Museum in Saint Petersburg, the world's largest art museum by gallery space, to honor individuals who support the arts and philanthropy. The date is believed to mark the birthday of Gaius Cilnius Maecenas, a Roman figure renowned for his patronage of the arts. The celebration highlights the contributions of notable Russian philanthropists such as Gavrila Solodovnikov, who bequeathed significant funds for societal needs, and the Tretyakov brothers, who co-founded the Tretyakov Gallery in Moscow. The inaugural celebration took place in 2005, organized by the State Hermitage Museum and other cultural entities, emphasizing the importance of recognizing patrons for their support of the arts in Russia. The day is informally referred to as Thank You Day, reflecting the need for society to express gratitude towards these benefactors.