Learn Swedish: Rådhuset ritades av en känd arkitekt. - The town hall was designed by a famous architect.

This is the s-passive in the simple past tense. The active past tense of the verb is ritade (a Group 1 verb meaning 'drew' or 'designed'). To make it passive, you simply add an -s to the end of that active past tense form, giving us ritades (was designed).

Doesn't the verb rita usually mean 'to draw'? Why is it translated as 'designed'?

It does usually mean 'to draw', but in Swedish, rita is the standard verb used for designing buildings, clothes, or furniture. Because an architect's design process involves drawing blueprints, a Swedish speaker will naturally say a building was ritades rather than using a word like designades.

Is av always the word used for 'by' in a passive sentence?

Yes! When you use a passive verb like ritades and want to introduce the 'agent' (the person or thing actually doing the action), you use av. It works exactly like 'by' in the English phrase 'designed by an architect'.

As a quick refresher, why is the adjective känd instead of känt or kända?