>>The Highland Games, From which the modern olympic descends...

I've got to disagree with that. The modern olympics derive from The Ancient Greek Olympics - and were held every four years at Olympia, a district of Elis. Any free Greek men were entitled to compete, you had to be able to speak Greek though. The first Olympic Games were held in 776 B.C. and the last in A.D. 393, when they were abolished by Emperor Theodosius. Who felt it an insult to Christianity.

There are lots of theories as to why the games were started, such as Hurcules honouring Zues or the rivalry between Pelops & Oinomaos, but the modern version certainly derives from ancient greek, not celtic tradition.