This is part of our weekly series, Lost Masterpieces, about the greatest buildings and works of art that were destroyed or never completed.

There are unfinished buildings all over the world, but the most mysterious—by far—is the Ryugyong Hotel in Pyongyang, the capital of North Korea.

Towering over the rest of the mid-rise city at more than 1,000 feet, the 105-story pyramid-shaped building with the ballpoint-pen top remains off-limits to the public, despite decades of construction and an estimated cost in the hundreds of millions of dollars.