Druids.
There's no such designation as "Celtic times". Celtic people are still around today, and have been around since before the Iron Age. Celtic civilization spans more than 2000 years, so you would need to be more specific about the era you're referring to.
Because they are knots created by the Celts
They were called round houses
The Celtic Sea is the area of the Atlantic Ocean due south of Ireland. The word Celt, simplified, refers to a group of tribes that originated in Ireland in the Iron ages. This is why the word Celt is associated with Ireland, as the term Gaelic is for Scotland. Therefore, it is called the Celtic Sea, because it is south of the country where Celts live.
The Druids
I believe London was started as a city by the Romans who Called it Londinium ( or something like that
the druids learned from the Celts :)
Druids.
The Celtic tribe created the Halloween holiday. It was known as All Hallow's Eve and Celtic priests known as the Druids presided over the celebration.
Druids are/were a part of the Celtic People.
druids
The Druids were a class of pagan priests in Celtic Britain and other parts of Celtic Europe. Very little is know about them as they left no written account of themselves and the only evidence for them is in the writing of Greek and Roman scholars.Greek and Roman writers did make many references to the use of human sacrifice by Druids. The modern view is that this is most likely Roman propaganda intended to discredit the Druids.Modern archaeological evidence suggests that human sacrifice was probably widespread throughout Celtic culture in general and not just by the Druids. Exactly who these groups were is not clear.
Druids were members of the priestly and learned classes of Western Europe, Britain and Ireland. They combined the duties of priest, scholar and teacher. The "civilization" also had warriors, who, at times of war, would use body paints. I do not know why they did this though but if you do please feel free to delete this.
The Druids are believed to have lived in several regions, primarily in Ancient Gaul (present-day France) and Britain. They were known as priests, scholars, and spiritual leaders among the Celtic people, and their influence extended across much of Western Europe during ancient times.
It would have to be present day Ireland. Remember, long before Rome fell, the Druids were driven from Gaul and outlawed in Britain. Many of the Druids, and their followers escaped to Ireland, or Hibernia, in Roman lingo. The Druids were the leaders of Celtic culture and the preservers of Celtic traditions and they found safety in Ireland's comparatively isolated location.
The druids, who were Celtic, did not use runes. The runes were used by the ancient Germanic tribes and the ancient Scandinavians.