IMHO, songs that have a historical basis (with a liberal smathering of poetic license) are the most interesting... Plus...

...they make for better intros 'cuase the singer/songwriter gets an opportunity to educate the audience about some aspect of history that the audience might find entertaining and educational...

I wrote a long (33 verses) song awhile back about a train that got buried in a tunnel underneath of Richmond, Virginia entitled the "Legend of the Churchill Tunnel" and it's about 50/50 fact and poetic/artistic license (I don't use the term mythology in terms of good song writing unless it is just that)...

B~