Wikipedia: "The Marktplatz dates from 1404, the year the Bremen Town Hall was completed. Before that, the market was held for more than 600 years on the square outside the Liebfrauenkirche. The Roland Statue was also erected the same year. During the following years, a stone wall was built between the inner and the outer areas of the square. The inner space, a circle, was used for the market. A rule was made which allowed only merchants whose vehicles could pass one of the seven openings in the wall to sell their products. The city council made this rule in order to ensure that there was sufficient space for pedestrians between the market stalls.
Around the middle of the 18th century, the wall was removed and replaced by a circle of columns. At the same time, the market place lost its outstanding importance as a centre of trade and commerce even though it continued to be used as a market for several decades. In 1836, the square was paved with sandstone. Inside the circle of columns, darker stones depicted a wheel with 10 spokes. At centre of the wheel, reddish stones form a Hanseatic Cross. With a diameter of 4.8 m (16 ft), it commemorates the importance of the Hanseatic Legion during the Wars of Liberation (1813-1815). Between February and June 2002, the paving was renewed without changing its historical layout."