The twenty remaining altars were renovated between the 17th and 19th centuries. The construction of the main altar and the eleven side altars in the second half of the 17th century was an absolute high point in the interior decoration. The altars often got another patron saint and received colours matching the taste of that time. There was no hesitation to use figures and ornaments of old-fashioned altars again.The altars originally embodied the prosperity of the medieval patriarchate but gradually developed into instruments of the local crafts and industries after the religious wars. One by one they decorated their location to their devoutness but above all to their financial means. The house of prayer was to reflect the same richness as their guild houses in the town centre.A number of altars was disassembled and stored in the nave, which functioned as a stonemason’s workplace during the restoration of the choir. The altars are submitted to tentative research and are restored according to the available financial means after which they are re-integrated. The budget for the interior restoration is however limited, so that the "Friends of St Nicholas’s church" need to approach potential sponsoring companies.

To enable the renovation of the lower church all altars will have to be moved to a warehouse outside the church. This allows for better research and protection and also prevents the altars from being damaged during the works.

. Numerous small furnishing objects such as lecterns, candleholders, confessional boxes, name catalogues and statues decorating the altars are awaiting their re-integration in the same way.