The Uwerk Zeit Device UR-1001, which retails for 345,000 Swiss Francs ($400,000), is one the world's most exquisite, intricate and expensive pocket watches. It's a watch lover's holy grail.

Swiss watchmaker Uwerk, which specializes in brawny-looking, high-end mechanical watches, unveiled the UR-1001 last year, but the device remains something of a wonder today.

Sporting 51 jewels, the UR-1001's steel body encases a modern marvel of mechanical expertise. It uses an usual set of gears and cubes to display accurate months and dates for an entire year and also features a day/night indicator. In fact, the mechanical "programming" even lets the watch accurately change dates between months with 30 days and months with 31. According to the video above, you'll only have to adjust the watch date once a year: in February, which usually lasts only 28 days.

The most impressive part about the UR-1001, which measures 4.17 inches x 2.44 inches x 0.9 inches, may be Urwerk's estimation of its lifespan. On the back is a 100-year dial; when it hits 100 years, a second linear calendar counts centuries, up to a full millennium. Just imagine an iPhone or Galaxy device with a similar dial.

Perhaps the UR-1001's only drawback is that it's not a self-winder. It can run 39 hours on a single wind, though, and its power reserve indicator includes a "red warning" zone to remind its owner when the pocket watch needs winding.

How much would you pay for a pocket watch that you could potentially give to your great-great-great grandchildren?