(CNN)Ancient sites that have survived centuries, or even millennia, haven’t fared so well in the 21st century.
The destruction at Palmyra in Syria, the Buddhas at Bamiyan in Afghanistan, and Nimrud’s ruins outside Mosul in Iraq show how precarious the future can be.
Here are 23 places that offer glimpses into humanity’s past, and the ingenuity that people brought to creating wonders without computers or heavy machinery.
While some are recognizable, others are easily accessible but lesser known.
Before the Sahara nearly swallowed the city and before French colonialists swept through, Timbuktu was one of the world’s most important centers of learning.
The city’s librarians guarded thousands of manuscripts, protecting them against the elements and violence.
Many of the manuscripts were evacuated to Mali’s capital Bamako during the last period of separatist violence, but the city’s unique mosques remain.
The three most important ones date as far back as the 14th century.
Their earthen architecture requires continuous maintenance, and caretakers today use the same techniques to preserve them as the original builders.