The best selling single of John Lennon's solo career was used as a teference by who to erect a memorial?
Imagine Peace Tower: The Imagine Peace Tower (Icelandic: "Friðarsúlan" , meaning "the peace column") is a memorial to John Lennon from his widow, Yoko Ono, located on Viðey Island in Kollafjörður Bay near Reykjavík, Iceland. Imagine Peace Tower:  These words, and the name of the tower, are a reference to Lennon's campaign for peace, and his song "Imagine". Imagine (John Lennon song):  The best-selling single of his solo career, its lyrics encourage the listener to imagine a world at peace without the barriers of borders or the divisions of religion and nationality, and to consider the possibility that the whole of humanity would live unattached to material possessions.
Yoko Ono