Jenny Holzer, "For SAAM," 2007, a time-based media sculpture comprised of vertical strands of white LEDs that reveal different text and patterns over a 24 hour cycle, located at the Smithsonian Museum of American Art.
Carved pillar at historic Urnes Stave Church, Norway
A German silver, gilt and rock crystal pillar sun dial with calendar, serving as a complete civil and religious compendium of time, by Wolfgang Fugger, c. 1563. Also, if you turn it just right, it opens up a hole in time and space. So be careful.