For the realization of a new sound system in the recent renovated Basilica of Tongeren, one of the oldest and most beautiful churches in Belgium, a sound system was required that not only sounds good in the acoustic difficult environment, but also looks good in the architectural heritage. The entire interior of the basilica is carved in marlstone, and to obtain the best architectural result, AUDAC accepted the challenge to develop speakers that look like they are carved from marl. As a base for the sound system, there is chosen for 12 pieces of the two meters long GIAX design column speakers and 4 pieces of the one meter long AXIR design column speakers. To become the coating method for the best possible result, a long experimental phase was required. In short, a marlstone of the basilica was crushed into powder, and after that the marl powder was applied to the speakers with a very special hand brushing technique. The final result is that we have column speakers that have the same color and structure as the marlstone interior of the basilica, and give the effect as if they were carved from marlstone. The amplification of this entire project is done with CPA series amplifiers, also from AUDAC. The audiovisual system is fully controlled by two AMX touch panels, whereof one is located in the sacristy, and the other can be placed on the altar. With these touch panels, the volume can be controlled from all microphones, including the wireless microphone systems, a recording of speech and music can be started, and the CD-player can be fully operated.