Интересно сравнить старый мост и новый мост.

new

Breakdown of Интересно сравнить старый мост и новый мост.

• и: and
• старый: old
• мост: the bridge

Questions & Answers about Интересно сравнить старый мост и новый мост.

What exactly does Интересно mean here? Is it “interesting” or “I wonder”?

In this sentence, Интересно means “(it is) interesting”, not “I wonder”.

• Интересно сравнить старый мост и новый мост.
  = It is interesting to compare the old bridge and the new bridge.

Russian often uses short neuter adjectives / words of state like Интересно, Скучно, Трудно, Легко in an impersonal way, roughly like English “It is interesting / boring / hard / easy”.

“I wonder” is another use of Интересно, usually followed by a clause with ли, что, etc., e.g.:

• Интересно, что он скажет. – I wonder what he will say.

That’s a different pattern from your sentence, which is Интересно + infinitive.

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Why is there no subject like “it” in the Russian sentence?