An ideal or perfect place where everyone lives in harmony is called what?

An ideal or perfect place where everyone lives in harmony is called Utopia, or a utopia.

The term is Latin, meaning 'nowhere', and originated with a book called Of the Best State of a Republic, and of the New Island Utopia, by Sir Thomas More, published in 1516, about a fictional Atlantic island More described as being a peaceful, tolerant society, apparently perfect in its social, legal and political systems.

More's book was based on Plato's Republic, and many other books have been written using similar concepts, in many styles.

Sir Thomas More was canonized by the Catholic Church and is also known as Saint Thomas More.