The Waag (Weigh House) is one of Alkmaar’s landmarks. The building has an interesting history dating back to the late 14th century. It was originally built as a chapel for the adjacent Holy Spirit hospital, where poor travelers could get free accommodation for three days and nights. In 1566 the Bishop of Haarlem gave permission to the Holy Spirit hospital to re-purpose the hospital building for weighing. In 1582, the weighing activities were moved to the larger Holy Spirit Chapel, which by then was no longer being used for divine services.

The conversion of the chapel to the weighing house was completed in 1583. The choir of the chapel was removed and a richly decorated façade in Renaissance style with a finely worked gable was constructed. Between 1597 and 1603, the original tower was replaced by the much larger present Waagtoren. Since the 19th century the building has been embellished with a painting on volcanic rock, reflecting trade and industry.

Nowadays the building houses the local tourist office and the Dutch Cheese Museum). The Waag - a national monument - is located at the Waagplein; where from April till September the famous cheese market is held.