The illustrious Beethoven Orchestra Bonn arrives at George Mason University on Saturday with an all-Beethoven program guaranteed to enchant the composer’s followers. Maestro Stefan Blunier conducts a program that opens with the overture from “The Ruins of Athens” and includes Symphony No. 7 in A major. French-Canadian pianist Louis Lortie, one of the world’s finest interpreters of Beethoven’s music, will perform his Piano Concerto No. 4 in G major.