This beautifully designed star-shaped fort was the premier defense system of the late 1500s.

A radio telescope for listening to the stars, based in one of the cloudiest countries in the world.

This large sand dune in the Netherlands is home to wind-whipped trees with "floating" roots.

An enigmatic monument to the Irish revolutionary who plotted an uprising against British rule.

The modern birthplace of Irish freedom.

The somber sculptures commemorating Irish Famine on the river Liffey in Dublin.

This courtly monument celebrates an influential comedian who turned taking the piss out of the powers-that-be into an art.

The house where the writer spent his formative years.

The comedy and tragedy of Oscar Wilde is preserved in a Dublin park, captured in a sculpture of colorful stone.

The enchanting archway is the only surviving portal into Dublin's lost medieval wall.

Amidst the bustling streets of Dublin, there is a hushed garden that is dedicated to "All those who gave their lives in the cause of Irish Freedom."

An 80-year-old plane tree is devouring an iron bench at Ireland's oldest law school.

The mummified heart of a saint lives on in this church—after a brief hiatus when it was stolen.

A strange egg in a mucky bog of western Ireland marks the spot of an aviation milestone.

This singular Irish dolmen is more Frank Lloyd Wright than upright stonehenge.

Originally built to monitor fishing, this Victorian tower now educates visitors about the local salmon industry.

Modern sundial uses ancient methods to tell time and date perfectly.

The world of the ancient Celtic civilization explained through a bewitching 11 acre garden.

The ruins of an 800-year-old monastery boasts the tallest round tower in Ireland.

One of the most popular megalithic sites in Ireland stands as a humbler version of Stonehenge.

Ireland's most remarkable collection of these curious cone-shaped houses is worth the buzz.

A proud bronze billy stands as an eternal symbol of Ireland's oldest festival, where a goat is made king.

An important landmark in the history of algebraic logic.

One of the Leiden's oldest pubs is also the birthplace of the Heineken star.