In the early days of watchmaking, when watches were carried in pockets or worn as brooches or necklaces, all types were round and a rectangular timepiece would have been laughed at!
Wall clocks, sundials and monumental clocks are all round, as are the majority of watches, simply because the hands and digits suit a circular space.
Featured model:
Blanc Pain, Ultra-Slim in steel and diamonds with black dial, rubber strap and automatic winding movement. www.blancpain.com