The oldest exhibits in the Clock Museum date to the 15th century. Amongst the highlights are the astronomical art clock by David a Sancto Cajetano from the 18th century. With sensational precision, the technical masterpiece shows the time as well as the length of the day and the orbital period of planets. The world-famous Laterndluhr style regulations are witnesses to the heyday of the art of Viennese clockmaking. The smallest clock is a "Zappler" and fits under a thimble; the heaviest example is the tower clock of St. Stephen’s Cathedral made from solid cast iron.

The exquisite inventory of the Clock Museum founded in 1917 can largely be traced back to two private collections: that of the middle-school teacher and first leader of the house, Rudolf Kafan, and the especially valuable collection of the writer Marie von Ebner-Eschenbach.