Complex sentence: It is in the United Nations permanent collection of art. In 1965 Keane was named "one of the most controversial and most successful painters at work today", with his works owned by many celebrities and hanging in a number of permanent collections.
Split into simpler sentences: It is in the United Nations permanent collection of art. In 1965 Keane was named "one of the most controversial and most successful painters at work today". The artworks was owned by many celebrities and hanging in a number of permanent collections.