Why is Christmas in December?
Origins of Christianity in Germany's historic cities
December 25th, the day of the winter solstice, used to be a particularly important day in many cultures. While the Middle East celebrated the birth of the Indian sun god on this day, the Egyptians celebrated the birth of Horus in the Isis cult. The Romans worshiped various gods for more than 1200 years, also foreign deities such as the Egyptian goddess Isis. During excavations in Mainz, remains of an Isis and Magna sacred site were found which were preserved and can be visited. Romans began their celebrations in honor of the invincible sun god Saturn also on December 25th. In addition, the Germanic peoples celebrated their midwinter festival which is still known today in Scandinavia as Yule.
In 217, Hyppolitus of Rome tried to eliminate these cults by moving the celebration of Christ's birth to December 25th. The meaning of Christmas was defined: It is the birth of Christ, the winter solstice in world history which gives us the certainty within all the ups and downs of history that the dark forces do not have the final power.
Trier is the oldest bishopric in Germany, bishops already existed in the city as early as in late antiquity. The “Trierer Dom” (Cathedral of Trier) is a UNESCO World Heritage Site, its interior holds the robe of Jesus Christ: The Holy Robe. In the Benedictine Abbey St Matthias, there are the tombs of the first bishops Eucharius and Valerius. In addition, there is the tomb of Saint Matthias the Apostle, the only burial of an apostle north of the Alps.
At the same time, the Council of Mainz declared Easter and Pentecost as important Christian festivals of the liturgical year. The Christian Christmas was meant to begin with the four-week long preparation time of Advent and last until the day of Epiphany on January 6. 
Even though the cathedrals of the former church leaders and sovereigns are no longer centers of power nowadays, what remains is the impressive appearance of the important monuments of Christianity, creating the atmospheric background for unique Christmas markets. To this day, people from all over the world with different religious backgrounds meet here at the end of each year, making the speed of time slow down abruptly.
A special attraction of 
The traditional Koblenz Christmas market is one of the largest and most
beautiful in Rhineland-Palatinate and takes place in the picturesque ambiance of
the romantic Old Town throughout the shopping streets. There is everything your
heart could desire at Christmas among the 130 and more stalls with handmade
arts, Christmas decorations and a massive selection of gift articles. Seasonally
decorated with the scent of gingerbread and mulled wine in the air and Christmas
melodies in the picturesque ambiance of the romantic Old Town: that is the
Koblenz Christmas market. An extensive range of handmade crafts and Christmas
decorations along with a huge selection of gift items are waiting for the
visitors each year. Rounded off with an extensive program with live concerts called "Christmas Vokal",
the Christmas bakery and many more attractions; a visit to the Koblenz Christmas
market is an experience you will not want to miss.
Every year, on the last Monday in November at 5 p.m., the "Christ Child" makes a special visit to Heidelberg's "Marktplatz" (Market Square) to festively open the Heidelberg Christmas Market. From then through December 22nd, the Old Town is aglow with the enchantment of Christmas. More than 140 special stands fill Heidelberg's large and small squares with an endless variety of everything that makes the season so unique. With a cup of hot mulled wine to warm the hand and heart, and delicious treats from the wide range of the region's gastronomic offerings, a leisurely stroll through the fairytale setting at the foot of the castle ruins is an unforgettable experience. 
A special attraction of Osnabrück's Christmas market is the largest Christmas music box in the world. Atmospheric bright lights illuminate the Old Town as a lovingly restored children's merry-go-round from 1907 turns and festively decorated stalls offer craftwork, wooden toys, or sweets. St. Nikolaus visits each day to open a window on the huge Advent calendar in front of the "Rathaus" (Town Hall) where Osnabrück's Treaty of the Peace of Westphalia was signed in 1648.
The Freiburg Christmas Market on the "Rathausplatz" (Town Hall Square) in the heart of the Old Town is considered one of the most beautiful Christmas markets in the whole of Germany. Framed by the Gothic cloister of the one-time Franciscan monastery, the nave of the "St. Martinskirche" (St. Martin's Church) and the picturesque, newly renovated facades of the new and old town halls, an enchanting collection of little houses is erected four weeks before Christmas. The Freiburg Christmas market is very much part of a tradition of Black Forest Christmas Markets. 
Münster's Christmas markets are unique: over 250 stands and festive illumination await the visitors in the wonderful atmosphere of the historical Old Town. The Christmas markets stand in rows along the market streets like pearls in a chain. They are just a few minutes walk from each other. 
Augsburg's Christkindlesmarkt radiates the charm of the holiday season with more than 500 years of tradition. Every weekend evening, the impressive Renaissance "Rathaus" (Town Hall) turns into a huge Advent calendar as twenty-four angels make music while standing in the windows of the Renaissance structure.
Erfurt's historic Old Town and the "Mariendom" (St Mary's Cathedral) where Martin Luther was ordained as a priest in 1511) provide a magical atmosphere at Christmas time and the "Domplatz" (Cathedral Square) is an ideal place for the Christmas market with a tradition of more than 150 years. Craftsmen sell a wide range of Thuringian handicrafts from Christmas tree decorations to blue print textiles and a rich choice of ceramics and pottery. 
The picturesque "Schlossplatz" (Palace Square) forms the fascinating setting for the Wiesbaden Twinkling Star Christmas Market. Four gates decorated with stars grant access to this fairytale like scene, where young and old will find desirable and beautiful items. Not only will the ambiance provide for a cheerful mood, but so will the accompanying program comprising choirs, nativity plays, wind quartets, concerts, storytelling and much more.
As Germany's oldest city, Trier's glorious history can be witnessed at every step on a stroll through the bustling Old Town that is made particularly inviting for the holidays. The "Hauptmarkt" (Main Market) and the "Dom" (Cathedral) present themselves as a picturesque backdrop for the annual Christmas market. 
The Rostock Christmas Market is the largest in Northern Germany. The colorful fair offers seasonal treasures such as "Rostocker Bratwurst" (fried sausage) and "Backbanane" (banana baked in dough) as well as traditional craftwork, music and a Ferris wheel. The market begins with the anticipated arrival of Santa Claus and his wife on a sailing ship. Santa then will give presents to the children while his wife is telling fairy tales.
The historic market square in Mainz is a blaze of lights. The air is scented
with a Christmassy mixture of roast almonds, gingerbread, hot chestnuts and
mulled wine. Large and small visitors gladly let themselves be enchanted by this
pre-Christmas atmosphere. On a stroll through Mainz Christmas market, the stress
and hectic pace of everyday life are quickly forgotten.
Würzburg is the northern gateway to the Romantic Road. In the heart of Old Town, one of Germany's most picturesque and enchanting Christmas markets carries on a tradition of holiday cheer dating from the early 19th century and provides a charming scene fit for a Christmas card with its Gothic Chapel. 