Kõpu Lighthouse s one of the best known symbols and tourist sights on the Estonian island of Hiiumaa. It is one of the oldest lighthouses in the world, having been in continuous use since its completion in 1531.
The most important East–West shipping lane in the Baltic Sea passed the Hiiu sandbank. Already before the year 1490 the Hanseatic merchants were seeking permission to mark this peninsula with an outstanding landmark. On 20 April 1500 Bishop Johannes III Orgas (John Orgies) agreed to allow a massive stone pillar without any openings. To cover the building costs, Tallinn city council had to establish a special lighthouse tax until the sum was complete. After couple of interruptions and major costs a fire was first lit in the autumn of 1531; it was simply a bonfire on top of the tower.
In August 1649 a wooden staircase was built to the outside wall of the tower and an open iron fire grate affixed to the top. Originally it was planned to burn coal in the lighthouse, but due to high transport costs of coal, wood was used instead. Several reconstructions were made by Swedish and Russian Empires between 17th and 21th centuries. A new light system was bought at the 1900 Paris World Fair, for three million gold rubles. The new apparatus (including the light chamber) was made by Sautter, Marlé & Co. It used a kerosene lamp with a gas mantle.
Kõpu Lighthouse only lost its important role as a primary navigation aid in 1997, when a radar lighthouse took over its duties. Recreational craft and small fishing vessels continue to rely on Kõpu for navigating, as a backup to electronic navigation systems. The Estonian Maritime Administration still classifies it as an active aid to navigation. Its future is ensured by its status as a protected cultural memorial.
Due to its enduring popularity and memorable shape, it is often used as a symbol of Hiiumaa. A major tourist attraction, the tower has been open for tourists since 1999. Together with the nearby Ristna lighthouse, the Kõpu lighthouse was commemorated on a postage stamp in 2000.
The Petersberg Citadel is one of the largest extant early-modern citadels in Europe and covers the whole north-western part of the Erfurt city centre. It was built after 1665 on Petersberg hill and was in military use until 1963. It dates from a time when Erfurt was ruled by the Electors of Mainz and is a unique example of the European style of fortress construction. Beneath the citadel is an underground maze of passageways that can be visited on guided tours organised by Erfurt Tourist Office.
The citadel was originally built on the site of a medieval Benedictine Monastery and the earliest parts of the complex date from the 12th century. Erfurt has also been ruled by Sweden, Prussia, Napoleon, the German Empire, the Nazis, and post-World War II Soviet occupying forces, and it was part of the German Democratic Republic (East Germany). All of these regimes used Petersberg Citadel and had an influence on its development. The baroque fortress was in military use until 1963. Since German reunification in 1990, the citadel has undergone significant restoration and it is now open to the public as a historic site.