Halcyon
Adjective:
- denoting a period of time in the past that was idyllically happy and peaceful.
Noun:
- a tropical Asian and African kingfisher with brightly colored plumage.
- a mythical bird said by ancient writers to breed in a nest floating at sea at the winter solstice, charming the wind and wave into calm.
(from writerscircle.com)
More historical info and examples here:
http://www.phrases.org.uk/meanings/halcyon-days.html