Large, airy hallways hide within an impenetrable fortress that beckons urban explorers.

The remains of the last Bosnian fortress to fall to the Ottomans are still standing.

The castle was reconstructed to fit Kaiser Wilhelm II's romanticized vision of the Middle Ages.

A well preserved medieval fortress in Vojvodina.

A small island in Lake Garda that was used as a burial site, pirate hideout, and a monastery.

This magnificent castle grew from a small Moorish fortress, and reportedly inspired two iconic Disney castles.

One of the most well-preserved castles in Italy also contains a rare medieval example of a port fortification.

A waterway covered over after the Industrial Revolution has been unearthed and cleaned up, for the enjoyment of fish and humans alike.

This 13th century Gothic brick castle is the largest in the world by surface area.

This 700-year-old structure is one of the most unique architectural and historic monuments in Gdańsk.

A semi-abandoned village destroyed by U.S. bombings during World War II dominates the valley of Turano.

This fantastic cave remained unexplored until 1948 when three schoolboys discovered a hidden entrance.

This trio of stone spires claims to be the only preserved medieval execution site in Europe.

A catapult rock from Gotland’s 13th-century civil war is still lodged in Scandinavia's best-preserved medieval city wall.

This seaside pine grove features an exclusive watchtower that presents amazing views.

A clerical error gave rise to this imaginary micronation in the southwestern corner of Estonia.

Largest island in the Baltic Sea experiences such idyllic weather that roses bloom in the middle of December.

Latvia's symbolic mountain-shaped national library is home to millions of cultural tomes.

This ducal residence was once home to a future Russian empress and a French king in exile.

This serene, turquoise lake in an extraordinary nature reserve showcases a rare natural phenomenon.

Legend says lovers who hold hands while venturing along this stone jetty and kiss at the end will remain together forever.

This stunning limestone waterfall is the highest in Estonia.

A secluded art gallery hidden within the cellars beneath Tallinn’s medieval monastery.

The widest natural waterfall in Estonia is a sight to see in all seasons.