fascinating they may be as history 
(ROOT (ADJP (JJ fascinating) (SBAR (S (NP (PRP they)) (VP (MD may) (VP (VB be) (PP (IN as) (NP (NN history)))))))))
(ROOT (ADJP (JJ ) (SBAR (S (NP (PRP )) (VP (MD ) (VP (VB ) (PP (IN ) (NP (NN )))))))))