Without a doubt, one of the most influencial composers of his day spanning the classical and romantic era, here is the last movement of his famous symphony no. 9 in d minor, mvt. 4 "Choral" containing the famous "Ode to Joy" melody.  This piece is one of the most revered pieces ever written, representing freedom worldwide. 

If you really want to learn more about Beethoven, read his biography here

• Ninth Symphony-final movement (1 of 5)   (  PDF )
• Ninth Symphony-final movement (2 of 5)   (  PDF )
• Ninth Symphony-final movement (3 of 5)   (  PDF )
• Ninth Symphony-final movement (4 of 5)   (  PDF )
• Ninth Sympnhony-final movement (5 of 5)   (  PDF )

Download this portion of the symphony on itunes by clicking here:
 

Here is an awesome CD of Symphony No. 9 on amazon.com: