Agents Fox Mulder and Dana Scully would appreciate the mysterious dancing orbs of Marfa, Texas, which have been seen in the sky near town since the mid-1800s. Called simply the Marfa Lights, the effect remains an unsolved phenomenon with random basketball-size blobs of energy appearing in pairs or groups and bouncing in the night sky around town. The Marfa Lights Viewing Area, a stone and stucco structure built by the Texas Department of Transportation, provides an optimal blob-watching perch nine miles east of Marfa on highway 90.

The New Age capital of the Southwest has hosted alien fanatics for decades, perhaps most notably in 1987 when hundreds of "Harmonic Convergence" believers waited at an area rock formation for a UFO to show itself. (It didn't happen.) Today, restaurants and gift shops continue to play up the alien theme, and hikes to energized vortices are among the most popular of inter-dimensional activities in the area.

Thanks to Steven Spielberg's 1977 film "Close Encounters of the Third Kind," popular culture might forever associate this geologic wonder with the strange and the otherworldly. Indeed, in that movie, the 1,000-foot-high monolith serves as the landing site for a massive alien mothership that releases human abductees. Today, rock climbers ascending the Tower's smooth sides and basalt columns are the only ones getting high off the ground at the Monument, a preserve operated by the National Park Service.

As the only town along Nevada State Route 375—aka the Extraterrestrial Highway, 98 empty miles that run near the top-secret military base known as Area 51—Rachel stands as the region's epicenter for all things alien-related. Visitors' first stop in the town of less than 100 is often the Little A'Le'Inn, a bar and restaurant with extraterrestrial-themed mixed drinks, T-shirts, trinkets and beer-sipping locals who might point you to preferred UFO viewing areas. The town hosts events year-round the likes of the E.T. Full Moon Midnight Marathon, a race along Extraterrestrial Highway this year on the weekend of August 16.

Towering to 14,411 feet, the snowy stratovolcano of Mount Rainier is among the most striking mountain peaks in the country. It's also the site of an incident involving Kenneth Arnold, a businessman s into the national lexicon.

Hovering conical shapes. Bright lights. A dark and misty English woods. This was the scene in 1980 for "Britain's Roswell" incident, a purported UFO contact in the Rendlesham Forest preserve of Suffolk, England, where military officers and local law enforcement are rumored to have rendezvoused with a craft. Now, almost three decades past, conspiracy theories persist on military entanglement and secret documents, some of which were recently declassified under a Freedom of Information Act request looking to solve the mystery once and for all.

The idiosyncratic iconography on an ancient tomb lid found at Palenque in the Mexican state of Chiapas has for decades cast speculation of the ancient Maya and their involvement with beings from out of this world. Dubbed the "Palenque Astronaut," the image shows a seated Mayan ruler in what some think is a space craft. Interpretations cite the cryptic carving as containing depictions of ignition and braking systems, a head rest, an engine and a oxygen nozzle pressed against the pilot's upturned nose.

Noted as being "among archaeology's greatest enigmas" by the United Nations Educational Scientific and Cultural Organisation (UNESCO), the giant geoglyphs of Peru's Nazca Desert have long been seen as signs of either aliens or the gods above. Scratched on the ground about 2,000 years ago, the images of creatures, plants and geometric figures arc hundreds of feet across dirt and sand. They are nearly imperceptible on the ground, though take shape as objects of art when seen from an airplane... or a UFO.

Was the greatest explosion in recent history caused by a UFO crash? That's one theory behind the Tunguska Event, a monumental blast in 1908 that was thousands of times more powerful than an atomic bomb, flattening millions of trees and sending shockwaves for hundreds of miles from its epicenter in the wilderness of Siberia's Krasnoyarsk Krai region. Dubbed the "Russian Roswell," UFO believers cite wreckage recovered from the blast zone. Other theories point to meteors, comets and even a black hole as the cause of the catastrophe. Conveniently, the Trans-Siberian Railway stops in Krasnoyarsk.

Dusty and remote, this southeast New Mexico city will be forever linked to "The Roswell Incident," a purported flying saucer crash in July of 1947. Government-conspiracy types tout alien autopsies and covert military operations associated with the event. Despite initial reports to the contrary, the U.S. government maintains it was merely a weather balloon. Decide for yourself at the International UFO Museum and Research Center, a museum and gift shop in town.

In 1973, a French singer, journalist and race car driver named Claude Vorilhon was abducted by aliens and told the secrets of the universe. Vorilhon renamed himself "Rael" and began teaching the truth—that humans were created by aliens who were mistakenly seen as gods by our primitive forebears. When humankind is sufficiently advanced, these aliens will return to our planet. And to make them feel welcome, Raelians plans to build an intergalactic embassy, tentatively scheduled to open in Jerusalem in 2035. While you're waiting, Raelian gatherings are held in several dozen countries worldwide throughout the year.