De Waag is a fifteenth-century city gate left standing alone in the middle of a square, and it is the oldest surviving building in Amsterdam outside the churches. Its first stone went down in 1488, when it was the Sint Antoniespoort, one of three main entrances through a new brick wall. The gate was set at about eight degrees to the street behind it, so that a cannon aimed at the opening could not fire straight into the city. Its towers held prisoners in peacetime.
The city outgrew its walls after 1612 and the gate was left on open ground. The courtyard between its two gateways was roofed over in 1617 and it became a weigh house for heavy goods: tobacco bales, anchors, cannon. Guilds took the upper floors — smiths, painters, masons, surgeons — each with its own small door and its emblem cut in stone above it. The surgeons dissected here in front of a paying audience. The ground floor is a café and restaurant now, and the rooms above are closed.