Please help, translation, passive form

[iaai]

Hi, I'm studying the passive form, and have come across this setence construction:
ベニスは水の都と呼ばれている。

Am I correct in thinking that this means Venice is called/known as the water capital ?
It's the (passive form)~ている bit that I don't get. I really need help with this, thank you!!

[QuackingShoe]

Yes.

[iaai]

Then...why is the passive form being used here?

[QuackingShoe]

"Venice is called" is passive in English. It's passive in Japanese too.

http://en.wikipedia.org/wiki/Passive_voice

[iaai]

So why not just say
ベニスは水の都と呼んでいる。 ? (non-passive)

[QuackingShoe]

Because that would translate "Venice is calling it 'City of Water'".

[iaai]

Ah got it! Thanks a lot

[QuackingShoe]

I can't type in Japanese at the moment, so you'll have to forgive my romaji.

So, to elaborate. The point of the passive is that instead of the subject of the sentence doing the action, it receives the action. In an active sentence, it would be the direct object, which in Japanese would generally be marked by wo.

An active sentence: I ate the apple. watashi ga ringo wo tabeta.
A passive sentence: The apple was eaten by me. ringo ga watashi ni taberareta.

An active sentence: Someone calls Venice "The City of Water." dareka ga benisu wo mizu no miyako to yondeiru.
A passive sentence: Venice is called "The City of Water" (by someone). benisu ga (dareka ni) mizu no miyako to yobareteiru.

I'm artificially avoiding dropping words or using 'ha' so as to illustrate the particular grammar point...

[iaai]

You, sir, are a legend.