Two years ago, the mayor of Venice asked UNESCO to put his city on the List of World Heritage in Danger. This cry for help came due to overtourism in the northern Italy city, especially from cruise ships. These have now been banned. But will Venice keep its original UNESCO title? The World Heritage Committee will decide in July whether Venice still needs to be put on the endangered list.

The rock formation known as Stonehenge in southern England has been a UNESCO World Heritage Site since 1986. Dating back more than 4,000 years, the site attracts almost one million tourists each year. But construction of the A303 highway, which passes directly in front of the megalithic structure and connects the towns of Berwick and Amesbury, could relegate Stonehenge to the red list.

Lake Ohrid is the oldest lake in Europe and one of the most ancient in the world. Researchers date it around 1.36 million years of age. Most of Lake Ohrid is part of North Macedonia while a smaller part belongs to Albania. In 1979, UNESCO elevated the ancient lake to World Heritage status. But due to large-scale tourism, it is now threatened with being put on the red list.

Auschwitz-Birkenau has been designated a UNESCO World Heritage Site in 1979. More than 1.1 million people were murdered at this Nazi death camp alone. However, the World Heritage Committee criticizes the fact that major nearby transport infrastructure projects could tarnish the solemn character of the memorial site, adding that local authorities have not responded to these concerns.

After being designated a UNESCO World Heritage Site for 25 years, the volcanic region on the Kamchatka Peninsula in far-eastern Russia could be banished to the red list. The reasons are many: From illegal fishing to the unlawful exploitation of mineral resources such as gold to the destruction of wildlife habitat. These are some of the wide-ranging consequences of political mismanagement.

Kenya's oldest continuously inhabited city is around 750 years old, and its picturesque old town was added to the UNESCO World Heritage List 20 years ago. But charming Lamu Town on Lamu island is in danger of being placed on the red list as the city has a huge waste problem. Planned construction projects such as an oil pipeline and an airport are making things worse.

The Great Barrier Reef was awarded UNESCO World Heritage status in 1981. It consists of almost 3,000 individual coral reefs and extends for about 2,300 kilometers (1,430 miles). But due to climate change and rising water temperatures, it has lost more than half of its coral. Storms, gas drilling and shipwrecks also pose threats to the World Heritage status of the underwater wonderworld.

The largest mangrove forests on earth cover an area of more than 10,000 square kilometers, two-thirds of which are located in Bangladesh and one-third in India. The area is home to many endangered species such as the Bengal tiger and has been a UNESCO World Heritage Site since 1997. But due to poaching, water pollution, deforestation and rising sea levels, it might be placed on the red list.

Soon after it was awarded World Heritage status in 1982, UNESCO started criticizing "illegal activities” taking place in the largest controlled wildlife reserve in Africa. With too much tourism, increased exploitation of mineral resources, a controversial dam project and rampant animal poaching, Selous was placed on the red list in 2014. Will it now lose the World Heritage title?

Liverpool's Maritime Mercantile City is also facing its exclusion from the World Heritage List. Just eight years after it was awarded the title in 2004, it was already placed on the red list because the buildings were not adequately maintained. Construction projects in the surrounding areas also had a negative impact on the character of the site. The World Heritage title could now be withdrawn.

When Jews settled in Speyer in the 11th century, they built the Judenhof (Jewish courtyard), an ensemble of synagogue, women's synagogue and ritual bath. The ruins of the synagogue (left) and the adjoining women's synagogue (right) can still be seen today. Jewish religious services used to be held here. Women were able to follow the events via listening gaps in the partition wall.

The remains of the synagogue are described as the oldest standing Jewish cult building from the Middle Ages. Visitors can access the Judenhof via the small Schpira Museum with its archaeological exhibits. Schpira is the Hebrew name for Speyer. Worms was called Warmaisa (W is pronounced like U) and Mainz Magenza. These three cities were therefore shortened and called ShUM Cities.

Next to the synagogue ruins there is a mikveh. The Jewish ritual bath from the 12th century is the oldest facility of its kind in central Europe. Climbing down, a Romanesque portal leads to an anteroom with a stone bench, which may have served as a changing room. A further staircase leads to the water basin, 10 meters (32.8 ft) underground.

The synagogue in Worms is almost 1,000 years old and over the centuries was destroyed and rebuilt several times. During the Nazi era it fell victim to the November Pogrom in 1938 (also known as Kristallnacht). In 1961 the reconstruction took place. At that time there was no Jewish community, but today services are held here again.

This synagogue also consists of the main worship chamber and a women's synagogue (on the left behind the columned passageways). As in Speyer, there is an ensemble consisting of synagogue and mikvah in Worms. This was unusual at the time and is what makes the ShUM Cities so special. The mikveh in Worms is currently being restored and can therefore not be visited.

The Holy Sands (Heiliger Sand) in Worms is still very important for Jewish people worldwide. Many famous scholars and rabbis are buried here, for example, Rabbi Meir von Rothenburg. There are over 2,500 visible gravestones here. Some are almost 1,000 years old. This makes Heiliger Sand the oldest Jewish cemetery in Europe.

In Mainz, there are only a few traces of the great Jewish history left: a cemetery and remains of columns from the old synagogue (foreground picture). In 2010 a new, architecturally spectacular synagogue was built. It takes the form of the word "Kedushah" (sanctification), a prayer that pious Jews recite three times a day.

The worship hall is also impressive. The walls are gold-colored and decorated with Hebrew characters right up to the tower. Even the benches form a letter: Lamedh — the Hebrew L. The architect Manuel Herz designed the New Synagogue with the ShUM tradition in mind. Thus he dedicated his work to the famous Rabbi Gershom ben Jehuda from Mainz.

With the support of the state of Rhineland-Palatinate and the Jewish community, the three cities want their Jewish heritage declared a World Heritage and have submitted an application to UNESCO. Susanne Urban of the SchUM-association believes the SchUM-tradition can be successful because it fulfills the required criterion "filling the gaps". So far there are only a few Jewish World Heritage Sites.

The healing power of water is at the center of every spa treatment. Seven mineral-rich healing springs bubble up in and around Bad Kissingen in Bavaria. You can bathe in the spring water, inhale it — or drink it. Freshly tapped water is available at this historic fountain bar with a foyer. It is served by fountain women who also advise the guests.

Pleasure has always been just as important as health. The desire to do something good for oneself led to a new form of tourism at the end of the 19th century. Aristocrats traveled through Europe and often spent weeks in one place. Tailored to their needs, sophisticated spa facilities, parks and hotels were created. Like the Kurhotel an der Lahn in Bad Ems in Rhineland-Palatinate.

European spa towns boasted entertainment galore, staging grand balls and artistic shows to amuse visitors. Throughout the summer months, aristocrats would come here to let their hair down and celebrate in style. Gambling — for example at Baden-Baden’s famous casino — was also hugely popular. Artists, musicians and poets like Fyodor Doystoevsky and Leo Tolstoy regularly joined the fun.

Special among Europe's spas are those in the West Bohemian Spa Triangle. Frantiskovy Lazne is the youngest and smallest of the three health resorts. It was only in the early 18th century that healing springs were discovered here. A hundred years later, Emperor Franz II had a magnificent spa built. Frantiskovy Lazne's reputation as a moor spa is legendary; it was one of the first in Europe.

The neighboring town Karlovy Vary is probably one of the most traditional health resorts in the world. Its springs were already used in the 14th century. 500 years later imperial personal physician Josef von Löscher made the place popular with an essay on the effect of healing waters. Karlovy Vary developed into one of the most fashionable health resorts in Europe.

The third spa resort is also glamorous and world-famous: Marianske Lazne. From the Habsburg Emperor Franz Joseph and the British King Edward to Richard Wagner, Johann Wolfgang von Goethe and Frederik Chopin, they were all here. In the historic Hotel Nove Lazne with its 225 luxury rooms, you can still book the historic imperial cabin today.

Today nobody says healing water; the term "spa" is more common. Spa, like the Belgian town of the same name. Three hundred springs helped the place to a rapid career. In the 18th and 19th centuries, spa buildings, a spa hall and, of course, a casino were built next to the fountains. Spa became the meeting place of crowned heads of Europe, which is why it was soon called "Café de l'Europe."

Water from Vichy is known all over the world. Without exaggerating you can say it is the foundation of the city and its soul. Louis XV and later the Bonapartes were treated here, and Napoleon III made Vichy his summer residence. This led to the construction of mansions, hotels, and later a huge thermal center with a drinking hall and a colonnade (photo), an Oriental-style bath and an opera house.

Halfway between Pisa and Florence lies Montecatini Terme. It has only 20,000 inhabitants and is the largest and most elegant health resort in Tuscany. Guests can choose from an array of 200 hotels of all categories and three thermal baths. The most beautiful is the Stabilimento Tettucio Spa. The entrance area alone takes visitors back in time.

In the 19th century, during construction work in Bath, the remains of a Roman bath house, the origins of bathing culture in the English spa town, were discovered by chance. The ancient complex was uncovered and opened to the public. For hygienic reasons, it is no longer possible to bathe here. To do this, visitors have to go next door to the modern Thermae Bath Spa, which opened in 2005.

Baden also looks back on a 2,000-year-old tradition, which was founded by the Romans. Here too, of course, Baden bei Wien developed its own characteristic spa architecture. But there is also modern architecture to admire. The largest free-hanging glass roof in Europe spans the Römertherme Baden. Below it, hot sulfurous healing water splashes, supplied by 14 springs.

Founded in 1899 by Hessian Grand Duke Ernst Ludwig to promote the arts and crafts movement — especially Bauhaus. Exhibitions began being staged at Mathildenhöhe as early as in 1901. The eclectic site comprises a historic Russian Orthodox Church, an exhibition hall, and Darmstadt's landmark Wedding Tower — built to commemorate Ernst Ludwig's second marriage.

Designed as an expansive defense network, the New Dutch Waterline encompasses 45 fortresses, six fortifications, various bunkers and waterworks, spanning over a total of 85 kilometers (53 miles). It was operational between 1815 and 1940, with the sole purpose of stopping enemies from advancing towards the western Netherlands.

Covering a staggering 482 hectares of land across no less than three provinces, Thailand's Kaeng Krachan forest complex is home to a wildlife sanctuary as well as two national parks. The area's biological diversity is regarded as exceptional. Indeed, it provides a habitat for several endangered species - including the Siamese crocodile, the Asian giant tortoise and the Asian black bear.

These Mongolian Bronze Age sculptures could soon be added to UNESCO's prestigious World Heritage Sites' list. The deer stones, as they are known, are engraved with highly artistic renderings of animals, weapons, shields and decorative patterns. Between one and four meters tall, the monuments are believed to have been dedicated to ancient chiefs and warriors.

The Roman Empire was protected by border fortifications known as the Limes. Three frontier sections have already made the World Heritage Sites list; the Lower Germanic Limes has not yet. Running 400 kilometers along river Rhine from Bonn to the Dutch coast, this military structure was established in the last decades B.C., lasting until the demise of the Western Roman Empire in the 5th century A.D.

This is Japan's Sannai-Maruyama site, containing remnants and reconstructions of a large Jomon-era settlement. This hunter-gatherer culture is thought to have lasted from about 13,000 B.C. to roughly 300 B.C.. Japan aims to have a total of 17 Jomon sites inscribed on the UNESCO World Cultural Heritage list.

The German cities of Speyer, Worms and Mainz — located near each other along river Rhine — were a center of Jewish cultural life in the Middle Ages. Referred to as Shin, Vav and Mem in medieval Hebrew, the three towns are collectively known as ShUM cities. Worms is home to Europe’s oldest Jewish cemetery (pictured above).

Europe boasts plenty of elegant spa towns — soon, 11 of them could be included on the World Heritage List. Among the contenders is the city of Bath in southwest England. Founded in the 1st century A.D., its well preserved ancient Roman Baths still flow with natural hot water. Other spa locations included on the application are in France, Germany, Austria, the Czech Republic, Italy and Belgium.

Peru's Chankillo complex, located some 360 kilometers north of the capital Lima, dates back to the early Horizon period (500 – 200 B#.C.). The Thirteen Towers (pictured) form a man-made horizon when viewed from below. The line of buildings, running north to south along a ridge, closely corresponds to the movement of the rising and setting sun over the year.

Extending 15 kilometers into the limestone foothills, Sof Omar is Ethiopia's longest cave. Situated in the country's southeast, it is venerated by local Muslims, with an annual November pilgrimage. Sof Omar features a spacious cavern known as the Chamber of Columns due to its colossal limestone pillars. The cave system is also home to various bats and fish.