CREATE TABLE table_27233 ("Week" FLOAT, "Date" CLOB, "Kickoff" CLOB, "Opponent" CLOB, "Final score" CLOB, "Team record" CLOB, "Game site" CLOB, "Attendance" FLOAT)

What opponents played Waldstadion in a game?
SELECT "Opponent" FROM table_27233 WHERE "Game site" = 'Waldstadion'
SELECT "Opponent" FROM "table_27233" WHERE "Game site" = 'Waldstadion'