Once I had a discussion with a friend. She told me that she didn’t like Heavy Metal, she only liked classical music. I asked her if she had ever listened to Heavy Metal? Because if she had , she would probably would have heard that Metal and Classical are really not that different, The only difference is the choice of instruments and the number of musicians.
I advised her to listen to Yngwie J Malmsteen. A Swedish Heavy Metal Guitarist who is a classically trained musician.
Concerto for Group and Orchestra is a live album by Deep Purple and the Royal Philharmonic Orchestra conducted by Malcolm Arnold, recorded at the Royal Albert Hall, London, in September 1969. It consists of a concerto composed by Jon Lord, with lyrics written by Ian Gillan. This is the first full length album to feature Ian Gillan on vocals and Roger Glover on bass. It was released on vinyl in December 1969.
These were just 2 examples, there are a great number of Metal bands whose basis lie in Classical music.