Sofia's legislative center is continuously reinventing itself.

A vast Communist-era exhibition space in the Bulgarian capital.

A striking symbol of the Bulgarian capital.

Balanced on four stone pillars, this historic tower was the site of a tragic political assassination.

Hidden just under the waters around this Turkish island are the ruins of a once great city.

Roman ruins, natural methane fires and a lovely beach.

In this historic region, homes and churches are carved into ancient volcanic rock formations.

The deepest underground city in Turkey was designed to protect 20,000 people behind massive stone doors.

A graveyard of old and rare planes that once were the glory of Persian aviation.

This circular Iranian jail was once a political prison run by the country's secret police.

Long before air conditioning, Persian architects found an ingenious way to cool off.

The fire inside this temple has burned for more than 1,500 years.

Putrefaction plateaus in Iran, where the dead were sent for decontamination before going to their final resting place.

The ancient necropolis houses the immense rock-cut tombs of four Persian kings.

Marked by the hand of the explorer Henry Morton Stanley.

The palace of the King of Kings, burned by Alexander the Great.

Named after a legendary garden called Eram in southern Arabia, built by order of Shaddad, an Arab king who wanted to compete with Paradise.

A spectacular rainbow of stained glass makes the "Pink Mosque" one of the most beautiful in Iran.

Mirrors and glass shards cover every inch of this arrestingly beautiful mosque.

The cathedral stands in New Jufa, Isfahan's Armenian quarter that was established in 1606.

17th century mosque for Shah Abbas' harem.

These little castles each held thousands of pigeons.

A 1,500-year-old, 3-story subterranean city where ancient Persians took refuge in times of war.

Despite a history of destruction, this former citadel survives to document Afghanistan's oft overlooked history.