If there’s one thing more difficult than building a grand complication, it is apparently, defining it. To break it down, a complication is known to be a horological feature that’s outside the simple display of hours, minutes and seconds. A grand complication then — to put it simply — is when several complications are fitted into the small confines of an average-sized timepiece.

Though experts are often divided on the “rules”, the term ‘grand complication’ traditionally involves complications from three families: timing, chiming and calendars. These include features such as the chronograph, perpetual calendar, minute repeater, moon phase, and grand sonnerie. Of course, more features involved means more chances of errors when making them work together.

But one thing’s for sure: successfully creating a grand complication is truly the pinnacle of a designer’s expertise and watchmaker’s skill. There’s a reason why they’re so expensive and rare. Besides paying for the poor lad that’s hunched over for months on end putting the pieces together into a case no bigger than your wrist, these watches are usually also bigger than usual, incurring additional costs.

Here, we take a look at five of these rare modern beauties, each a hallmark of haute horlogerie that is as impressive as it is complex.