Complex sentence: Thus the common assumption that Mozart's grave (see below) was unmarked because he was too poor is false: his burial in 1791 after a normal funeral in the Stephansdom simply followed the regulations of the day.
Split into simpler sentences: Thus the common assumption that Mozart's grave (see below) was unmarked because he was too poor is false. His burial in 1791 after a funeral in the Stephansdom simply followed the regulations of the day.