Learn Hardcore Russian: Дорога была построена раньше, чем дом. - The road was built earlier than the house.

The phrase была построена is the past passive voice, which emphasizes the road (дорога) as the subject and the completed action, rather than who performed it. In Russian, the passive past is formed with the auxiliary быть (in the past tense) + past passive participle. An active alternative could be Кто-то построил дорогу раньше, чем дом, but that shifts the focus onto the unnamed doer (кто-то).

How do you form the past passive participle построена?

Start with the perfective infinitive построить, remove -ть, add the suffix -ен- (or -ён- after certain consonants), and then attach the gender ending. Since дорога is feminine, you get:
постро- + ен- + а → построена.

Why is there a comma before чем? Is it always required?

Yes. In comparative constructions with a comparative adverb + чем (e.g., раньше, чем), a comma precedes чем to mark the comparison:
Я пришёл раньше, чем он.
Omitting the comma in standard written Russian in this context is considered incorrect.

What is the role of раньше, чем here? Can I just use раньше alone?

Раньше, чем means “earlier than” and is used for direct comparisons between two items or actions. Раньше alone means “earlier” and either needs context or a time expression in the genitive (e.g., раньше семи = “before seven o’clock”). To compare two nouns or clauses, you must include чем.

Can I replace раньше, чем with до того, как?

Yes. You can rephrase the sentence as:
Дорога была построена до того, как построили дом.
Here до того, как introduces a subordinate clause with its own verb (построили) and conveys the same sequence of events.

Could the word order be changed? For example, Раньше, чем дом, дорога была построена?

Absolutely. Russian allows flexible word order for emphasis. Placing Раньше, чем дом at the front highlights the comparison. The neutral order is Дорога была построена раньше, чем дом, but your version is grammatically correct and just stylistically different.

Why is дом in the nominative case after чем? Shouldn’t it be in the genitive?

In comparative constructions with чем, the compared noun remains in its normal case (often nominative if it’s a subject). Here дом is the subject of the implied clause “(дом был построен)”, so it stays nominative.

How would I mention who built the road in this passive sentence?

You add an agent in the instrumental case introduced by кем (optional):
Дорога была построена рабочими раньше, чем дом.
(“The road was built by the workers earlier than the house.”)