Felix Mendelssohn-Bartholdy : Wedding March, from A Midsummer Night's Dream
This Wedding March comes from Mendelssohn's the incidental music to A Midsummer Night's Dream. It became customary to play this at marriage ceremonies from about the mid 19th Century. You might also like to try the Bridal Chorus by Wagner.
If you can't see music above, then install the easy to use Scorch Plug-in from Sibelius software.