I came across one or two classical covers of rock songs over the years that stuck in my head.
Finding another one just now, I decided to hunt down a few more, and this is the list I came up with:
King Crimson - Court of the Crimson King - Mitteleuropa Orchestra
Tool - Forty-Six & 2 - Vitamin String Quartet
Metallica - One - Viola da gamba solo
Deep Purple - Smoke on the Water - Japanese traditional instruments with orchestral backing
Pink Floyd - Comfortably Numb - London Philharmonic Orchestra
Led Zepellin - Kashmir - Yamato String Quartet
... and another version by London Philharmonic Orchestra
ITT: share your favourite rock covers that use classical or traditional instruments!
A few more good ones I found
Frank Zappa - Peaches en Regalia - Talichova komorní filharmonie
Procol Harum - A Whiter Shade of Pale - London Symphony Orchestra