From the remains of Cleopatra's castle to the lost graves of towns inhabited a mere fifty years ago, these submerged wonders hide ruins under seas and rivers.

These seven secret architectural wonders house weapons facilities, bunkers, anonymous societies and dazzling temples in hidden spaces just out of sight.

These 7 destroyed wonders of recent architectural history once served as powerful symbols or landmarks, but were taken down by fire, war and other misfortunes.

7 of America's most amazing and mysterious attractions, from unexplained archaeological ruins to modern-day monuments with instructions for the post-apocalypse.

How could these 7 lost wonders of the written word, from Shakespeare to biblical gospels, have changed the world? Unfortunately, we'll never know.

These 7 Desconstructivist buildings by architects like Frank Gehry, Zaha Hadid and Daniel Libeskind defy conventions with odd shapes and confusing proportions.

There are the original 7 wonders, the new 7 wonders, and these 7 wonders: ancient man-made structures that amaze and inspire us with their complexity.

Here are 7 wondrous examples of epic modern ship design, all demonstrating that when it comes to innovation, technology and breadth of ambition, the best designs are the ones making waves.

We typically see burial places as solemn and sorrowful, but these seven amazing collections of human bones artistically remind us to embrace life every day.

Megaproject... even the word sounds big! These 7 amazing engineering wonders push the envelope of what can be accomplished on Earth - and someday, beyond.