As most people know, Denver falls within the Mountain time zone. That's because the 105th meridian, the imaginary lines developed in Greenwich, England, in 1851 that determine time zones, goes north to south down Kalamath Avenue.
The 105th meridian is halfway through the middle of the Mountain time zone (which is two hours behind New York, so when it’s high noon in New York, it’s 11 a.m. in Chicago, 10 a.m. in Denver and 9 a.m. in Los Angeles). While this may sound straightforward enough, political sensitivities have created jagged, irregular 
time zone boundaries.
Of course, when these imaginary lines running from the North Pole to the South Pole were invented, Denver didn’t even exist. The city wasn't founded until 1858.
One of the most humorous aspects of this is that the 105th meridian goes right through the center of Denver Union Station. There is a steel bar embedded in the paving of Wynkoop Plaza in front of the station showing the line of the 105th meridian line as it enters the station. A display panel inside the west doors of Union Station provides a history of meridian lines and shows how they work in setting time zones around the world.
Denver has another imaginary line that is equally interesting–the contour that is exactly 5,280 feet above sea level. (See "Only in Denver: Mile High Markers.") A contour line on a map joins points of equal elevation. Therefore, the contour line that is exactly one mile above sea level in Denver is not just one point, but actually passes through thousands of buildings as it winds its way around the city.
The most famous place the contour touches is the west steps of the Colorado State Capitol Building. The mile high contour also passes the mayor’s office, at several points near City Park and the contour continues down to Coors Field, where it passes through the Rooftop–the largest outdoor bar in any stadium in America. On a steel beam above the bar is a gigantic “5280,” indicating that the beam is exactly a mile above sea level. It's the perfect place to enjoy a Colorado craft beer and cheer on the mile high Colorado Rockies.