1972 Munich Olympic Token?

What is depicted in the upper image you will recognize :) and in the lower image you see the towers of the Frauenkirche, a prominent historic building in Munich http://en.wikipedia.org/wiki/Munich_Frauenkirche , in front of a globe. The motto means "Munich greets the sportspeople of the world".

The little "1000" below the church indicates the silver content. On many silver medals you will see "835", "925", etc. (the rest will then usually be copper to make the piece a little harder). So I think that yours is a pure silver medal - which does not necessarily mean it is worth much. Still a nice piece.

As for cleaning coins, the obvious advice would be to not rub them. Many collectors will leave their coins as they are (found ancients with lots of dirt are a different story). In this particular case - a modern medal which probably does not have much collectors value beyond the precious metal value - you could try a cleaning bath for coins; quite a few dealers will sell such silver baths. Now whether it's worth it ...

Christian