Eise Eisinga, a wool comber who was fascinated by astronomy, undertook in 1774 the construction of an ingenious device that made the movement of the stars appear on the ceiling of his living room (finished in 1781). He was able to achieve a surprisingly accurate representation of the heavens as perceived by 18 C astronomers. This planetarium, whose workings you will be able to examine in the attic, is the oldest one in Europe that is still functional.