The Waag (weighouse) was one of the most important secular buildings of the Middle Ages in Amsterdam. It was built as the Sint Antonies gate in 1488 in the eastern city wall which went along the Kloveniersburgwal to the Singel. In 1585 the city expanded and the gate lost its original purpose. From 1617-1618 onwards it has been used as a weighouse next to the old weighouse on the Dam. Several guilds used the rooms on the upper floor as assembly rooms. In the beginning the first entrance was separated from the main gate by a stone bridge over the canal. With the alteration this space was covered and used by the guild of the surgeons. This main room was altered in 1690-1691 and became the Theatrum Anatonicum with the central round tower. The weighouse was used until 1819 and the Theatrum Anatonicum until 1869.
Circa 1600 the water in front of and next to the former gate has been filled up by which the Nieuwmarkt or St. Antoniesmarkt came into being. At first the Nieuwmarkt mainly was a dairy market but in the 18th Century week- and year markets with clothes and textiles were held here (Bakker, B., Fleurbaay, E., Gerlagh, A.W., De verzameling Van Eeghen, Amsterdamse tekeningen 1600-1950, Zwolle 1988, p. 148, no. 103, p. 269, no. 257).