Arctic Circle
The Arctic Circle or Arctic was a region around the North Pole on Earth. The northernmost areas of the continents of Asia, Europe, and North America were located in this region.

In the late 17th century, the Arctic Circle, passing through the Kara Sea, was labeled on a map of Earth using its Latin name Circulus Arcticus. (, opening credits)

In 2063, the  pursued a Borg sphere to Earth from the 24th century through a Borg-created temporal vortex. The Borg had arrived to destroy the Phoenix, Zefram Cochrane's historic first warp-ed vessel. The Enterprise-E easily destroyed the sphere, though the Borg drones escaped. ()

Unknown to the Enterprise-E crew, much of the debris from the Borg sphere landed in the Arctic Circle. Nearly a hundred years later, an Earth Sciences Institute team discovered the debris field and recovered two Borg drones from beneath a glacier. The drones thawed and assimilated the researchers and their ship. ()

Appendices

Background information 
The 17th century map, known as "Harmonia macrocosmica seu atlas universalis et novus, totius universi creati cosmographiam generalem, et novam exhibens", was created by . A scan of the original can be found here.

According to a 21st century-era political map of Earth, seen in the remastered , the Arctic Circle was 66° 33ʹ north of the equator. This was a Central Intelligence Agency map published either in April 2007  or September 2008.  The difference, which was not noticeable at the resolution of the image from the episode, was the addition of Kosovo, which gained its independence between the releases. The label "Arctic Circle" was illegible to the viewer.

It was possible that the Arctic Circle was on two 20th century-era political maps of Earth used in the original "The Cage". However, due to the poor quality of the images and the inability to identity and access the source material for verification, this was far from certain.

This circle was located above 66 degrees north latitude on Earth. ()

External links 
 
 

de:Nördlicher Polarkreis
it:Circolo Polare Artico
nl:Noordpoolcirkel
Earth geography