Any tour of the Kölner Dom is incomplete without a visit to the sacristy, where the cathedral treasures are on display. The most important piece, for the inhabitants of Cologne, is a simple wooden staff, which, although it is decorated with ivory and silver, has no great value in financial terms. Its symbolic importance, however, is great: not only was it claimed to be the staff of St. Peter, which found its way to Cologne at the end of the 10th Century, but it was also the symbol of the power of the Archbishop over the city. Pieces of St. Peter's chains are said to be locked in a monstrance which is kept in the treasure-vault. On special occasions these treasures are carried through the city in a procession.