Avril Lavigne died years ago and was replaced by a double. 

Many people believe that Avril Lavigne died in 2003 and was replaced by a body double. Her name is Melissa. Some even believe that Melissa was a clone. It is rumored that Lavigne was using Melissa as a double before she passed away. The stress of being a celebrity was too much for her.

Theorists believe this is true because of the obvious differences in the women's faces. Others believe Lavigne simply got plastic surgery.

Aside from the facial differences, Melissa is said to dress differently than Lavigne. Around 2003, Lavigne's supposed death, Melissa wore dresses and skirts to red carpet events. Prior to this, Lavigne wore more pants and shorts to events.

The Denver Airport was built by Nazis, The Illuminati, maybe both, to hide secret activities. 

There are a few different theories about this enormous airport. Most theorists do not even understand why it was built in the first place because there was a fully functional airport closer to downtown.

Most theorists begin by trying to explain the creepy art all around the airport. The most famous statue is "Blue Mustang." This statue is a 32-foot tall horse with red glowing eyes. It is said that the statue fell on the artist and killed him.

There were also murals that depicted America submitting to Germany. One featured a Boy Scout handing his weapons to a Bavarian boy. Another showed a Nazi officer in a gas mask. Most of these murals have been covered up because of the controversy behind them.

The most controversy is around who built the airport, and why. A common belief is that it was built by a Nazi group, "New World Order." Plaques around the airport state that it was funded by the "New World Airport Commission." However, when researching this organization, nothing comes up. Since the names are so similar, people assume that it was, in fact, a group of Nazi's. To add fuel to the fire, when the runways are seen from an aerial view they resemble a swastika.

Some people believe that it is the Illuminati headquarters. The plaques have a Masonic square and compass signal; both are associated with the Illuminati. The date of the dedication is on March 19, 1944. If the numbers are all added together it makes 33, which is the highest level one can achieve in the Illuminati. They also suggest that the airport somehow messed up the building five times before getting it right. It is said that they buried these buildings and they now serve as the headquarters for the Illuminati.

Another theory suggests that there are underground bunkers to hide important world leaders in case of a disaster or apocalypse. There was a baggage system underground that did not work out. Instead of fixing it or getting rid of it for space it takes up they decided to leave it. They believe this was to hide the tunnels for a secret underground bunker.

Princess Diana's death was not an accident. 

Many people believe that her death was not an accident, but it was staged by Queen Elizabeth and the royal family.

Some believe that she was pregnant with an Egyptian-Muslim and the royal family did not want to risk mixing the bloodline. However, there was no sign of her being pregnant in the autopsy.

Diana herself believed that she would be murdered. She voiced concerns and even wrote about her fear of being killed in a car accident by someone else. Her bodyguard was killed shortly before she was in what she believed to be another conspiracy.

There is much controversy about the actual accident. Paparazzi has been blamed for the most part. However, it is unclear if the intentionally made a climate where Princess Diana would crash or the family used the situation to instigate a car crash.

While the paparazzi is widely to blame, the driver of the car was supposedly drunk. Some believe that he was not drunk at all and intentionally crashed the car. These conspirators even believe that the swapped out the bodies to falsify a positive toxicology report in the autopsy.

Some believe that there was a bright flash before the crash to disorient the driver and cause the accident. This is a popular technique with assassinations.