The main feature of this tower is the Jubilee Clock, which was added in 1930. This amazing astronomical clock was designed by Lier clockmaker Louis Zimmer. It houses 13 faces, respectively showing the Greenwich Mean Time, lunar cycle, the signs of the Zodiac, solar cycle, the seven days of the week, the globe with the meridians, the twelve months of the year, the eternal dates, the four seasons, the tidal waves in Lier, the age and the phases of the moon.

I have found this article that explains how the different dials work:
www http://en.wikipedia.org/wiki/Zimmer_tower