Paris Observatory. Engraving of the Paris Observa- tory, France, during the time of the Italian astronomer Giovanni Domenico Cassini (1625-1712). The observatory was funded by King Louis XIV and built during 1667-72. Cassini came to Paris in 1669 after being invited by French astronomer Jean Picard. Cassini quarrelled with the observatory's architect, Claude Perrault, arguing for a more practical design. At Paris Cassini discovered four satellites of Saturn and a division in that planet's rings. He also measured the distance to Mars, allowing the Earth-Sun distance to be calcu- lated. The next three generations of Cassini's descendents also worked at the Observatory.