The historical architecture of the town centre is one of the major attractions of Køge. The oldest dated half-timbered house in Denmark, which is also the oldest dated non-nobility and non-religious building of the nordic countries, can be found in Køge. It was built in 1527. Originally a section of a row of hovels, it is now a part of the public library. Pictures can be found in the gallery. The Third largest Viking Ring Fortress was found near the city of Køge, Denmark.[3]

Near the house is Sankt Nicolai Church. The tower of the church contains a lighthouse, the first to be built in Denmark.

Køge's town hall dates from 1552 and is the oldest town hall in Denmark still in use as such.

Køge Torv, the market square, is, with an area of almost 1 hectare (2.5 acres), the largest town square in Denmark outside Copenhagen and the largest and best-preserved medieval town square in Denmark. There are fair days on the square Wednesday and Saturday.