In the early 20th Century many of these pillars were placed in Dutch cities. It is a transformer box with the look of an advertising pillar. The outside of the pillar is for rent with advertisement posters. In this way the electricity company can earn some extra money. In the beginning they were made of steal but now of concrete. In popular language the dutch people call them "pepperboxes".
At the left side you see another one. The advertisement posters must have a cultural character as performances or exhibitions.