WEIRD HOLIDAYS

We’ve been adding an extra day to February since Julius Caesar overhauled the Roman calendar and implemented leap years in 46 BCE.

In the United States, children who leave a newly lost tooth under their pillow know to expect a nocturnal visit from the Tooth Fairy, who might leave a shiny quarter, a new toothbrush, or perhaps even a crisp $20 bill!

The Romans referred to the days of the month by their relation to the 'Kalends,' the 'Ides,' and the 'Nones.' If Caesar had been killed any other day, his famous warning might have sounded much less ominous.

Pi, a.k.a. the ratio of a circle's circumference to its diameter, is infinite. But a Google engineer has calculated the first 31 trillion digits of the figure just in time for Pi Day.

This holiday is mostly contained to the Great Lakes region, but for some retailers, its sales are better than those for Mother's Day.

Math whizzes may have noticed something particularly pleasing about today's date.

Free pizza is the best pizza.

In honor of World UFO Day (on July 2), here are 12 accounts of flying objects that remain fascinating for believers and skeptics alike.

Kissing under the mistletoe has roots in Nordic mythology.

Today is New Beer's Eve—time to pick out a brew for tomorrow's National Beer Day!

Leap Day comes just once every four years. Here's a list of eight events that occurred on this rare day.

You might not find any Hallmark cards for these holidays, but they're well worth celebrating.