It's hard to imagine that in 1945 many German cities were completely destroyed by bombs, as is the case in Iraq or Syria nowadays. Though practically everything has been rebuilt since, the remaining ruins in Germany now serve as reminders of the horrors of war. Many of them are religious buildings: Berlin's Kaiser Wilhelm Memorial Church is one of these stone witnesses.

Designed in Neo-Romanesque style and consecrated in 1895, Berlin's Kaiser Wilhelm Memorial Church burned down following an air raid by the Allies on November 23, 1943. Only the 71-meter high main tower could be preserved. The four-part ensemble of buildings surrounding it with the new Kaiser Wilhelm Memorial Church was inaugurated in late 1961. Both old and new parts are protected monuments.

The history of the Franciscan monastery church in Berlin's district of Mitte goes back to 1250. The monastery was dissolved during the Reformation in 1539. It was bombed on April 3, 1945. The ruined church needed to stabilized and it became the only building to survive the era. After its restoration, the ruin has been used for exhibitions, theater performances and concerts since 2004.

The church of St. Alban in the heart of Cologne was heavily destroyed, never to be rebuilt. Here is a view of the remains of the choir. The open former church serves as a memorial to the dead of the war. Inside, "The Mourning Parents," a sculpture by Ernst Barlach based on a drawing by Käthe Kollwitz, call to peace.

Not far from St. Alban was the Church of St. Kolumba, one of the oldest parish churches of Cologne. The foundation stone was laid in 980. After the almost total destruction of the church in 1943, only a few parts of the late medieval outer wall and statue of Mary were left in the rubble.

For this statue of the Virgin Mary, the octagonal chapel of St. Mary was built from 1947 to 1950 on the location of the ruins. The Cologners therefore refer to it as the "Madonna in the Ruins". In 1956-57, an additional square chapel was built as an extension to the first one. St. Kolumba was fully integrated into the newly created archiepiscopal museum of Cologne in 2007.

The Zerbst Castle in Saxony-Anhalt once was the residence of the princes of Anhalt-Zerbst. In the 17th century, a new building was planned as a three-winged facility. It was one of the most important baroque buildings in central Germany. The future Russian Empress Catherine II, born Princess Sophie Friederike Auguste von Anhalt-Zerbst, visited her relatives there quite often as a child.

In April 1945, the Zerbst Castle was hit by bombs and burned out completely. The sumptuous interior was lost. It would have been possible to reconstruct it, but the proposal was turned down for political reasons. Only the ruins of the east wing escaped demolition. It remains a goal to reconstruct their outer part in their original form.

It's not a ruin, but nevertheless a memorial: In Düsseldorf, a huge bunker was designed as a church for reasons of camouflage in the early 1940s. It finally became a church in 1949. The unique building is a protected monument, and is said to be the world's most stable place of worship. Today, the bunker is not only a church, but also a memorial and an art center.

Also unique in the world is this huge bunker in Hamburg-Wilhelmsburg. After the war, many of these constructions fell into decline. This former bunker was renovated a few years ago to be transformed into an "energy bunker." Equipped with a solar envelope and a regenerative power plant with large heat storage, the huge building now supplies the population with heat and electricity.

The origins of the St. Nicholas Church in Hamburg reach back to the year 1195. Following a fire in 1842, a completely new church in neo-Gothic style was built and completed in 1874. The 147-meter (482 ft) high tower was temporarily the tallest architectural structure in the world. Then came July 28, 1943: The spire served as a target marker during Allied air raids. St. Nikolai burned down.

Only the tower and the vault survived, remaining open wounds to this day. After the war, the Hamburg Senate decided not to rebuild the church. The ruins of St. Nicholas were dedicated to "the victims of war and tyranny between 1933 and 1945." In the basement, a documentation center was created with a permanent exhibition showing "Gomorrha1943 - The destruction of Hamburg in aerial warfare."

The Frauenkirche, the pearl of the Baroque city of Dresden and a splendid example of Protestant religious architecture, was left in ruins in 1945. It had been spared during the devastating bombing in February 1945. But the stone dome collapsed the next day. The rubble long served as a memorial of war and destruction. The East German government could not afford to reconstruct the majestic church.

After German reunification, reconstruction of the Frauenkirche began in 1996. It took nine years to be completed. Stones of the original building were incorporated into the new masonry. Involved in the financing of the 180-million-euro mammoth project were 16 German and foreign support associations, as well as donors from around the world - a strong symbol of hope and international understanding.

The restoration of the Auferstehungskirche, or Church of Resurrection, in Pforzheim, was completed in 1947. It was the first church rebuilt in Germany after the war, using the ruins of surrounding houses: 30,000 bricks were laboriously unearthed and cleaned. The church became a symbol of a new beginning and served as a model for 46 of the temporary churches set up in war-ravaged German cities.