In the Mathematisch-Physikalischer Salon (Royal Cabinet of Mathematical and Physical Instruments) the clocks are no ordinary ones. Take the world time clock constructed by Andreas Gärtner, for example: 365 supplementary dials are affixed to a large dial and show the time in 365 different locations on the earth. In about 1690 Andreas Gärtner found an amazing technical solution for the design of this clock – by utilizing the laws of gravity. Or take the spectacular astronomical clock. As early as the 1560s it was constructed in Marburg and Kassel on commission to Elector August of Saxony. It shows the position of the sun, moon, Mercury, Venus, Mars, Jupiter and Saturn in relation to the time of day – an astounding feat of technical expertise. These two clocks are among the many masterpieces in the world-famous collection of historic clocks and scientific instruments held in the Mathematisch-Physikalischer Salon (Royal Cabinet of Mathematical and Physical Instruments). Its holdings include terrestrial and celestial globes, fascinating optical, astronomical and geodetic devices dating back to the 16th century, as well as historic instruments for calculating, drawing and determining length, mass, temperature and air pressure. The objects provide an overview of the development of early precision mechanical devices, globes and clocks, and selected specimens demonstrate their application and their technical construction. In addition, they are works of art of the highest order, reflecting their princely origins. When the Mathematisch-Physikalischer Salon (Royal Cabinet of Mathematical and Physical Instruments) reopens in April 2013 after the current period of refurbishment the museum will show how the world was surveyed in past centuries. The Mathematisch-Physikalischer Salon (Royal Cabinet of Mathematical and Physical Instruments) is part of the Staatliche Kunstsammlungen Dresden (Dresden State Art Collections) that are among the most prominent museums in the world. The combined holdings of the twelve museums offer the visitor a remarkable thematic diversity. These museums originated from the collections of the Saxon electors and Polish kings. They systematically developed cabinets of curiosities, which were accessible to select circles in their day and still form the core of the wonderful art treasures of the Staatliche Kunstsammlungen Dresden today. The collections are situated in world famous buildings such as the Residenzschloss (Royal Palace), the Zwinger, and the Semperbau (Semper Building), which are among the most important sights in Dresden.