For my money, there’s no more beautiful wristwatch than those designed by Max Bill for Junghans in the middle of the 20th century.  Bill was a legendary designer, fine artist and teacher at the Bauhaus, possibly Switzerland’s greatest artist.  His watches reflect his clean early modern design — he believed mathematics could be a path to aesthetics.  They can be tough to find in the US, though they are sold at the Museum of Modern Art store.