Questions & Answers about Мы живём около главной площади.
What makes главной площади take the Genitive case in this sentence?
The preposition около (near/around) always requires the following noun and any attached adjectives to be in the Genitive case.
How do we form the Genitive case for a feminine adjective like главная (main)?
For most feminine adjectives in the Genitive case, the Nominative ending -ая changes to -ой. That is why главная becomes главной.
Doesn't the adjective ending -ой show up in other cases too?
Yes, it does! Russian uses the exact same -ой ending for feminine adjectives in four different cases: Genitive, Dative, Instrumental, and Prepositional. You have to rely on context clues, like the preposition около, to know which case is actually being used.
Площадь is a feminine noun, so why does it end in -и instead of -ы in the Genitive case?
Standard feminine nouns ending in -а or -я usually take -ы or -и in the Genitive. However, площадь belongs to a special group of feminine nouns that end in a soft sign (-ь). For these nouns, the Genitive ending is always -и, which replaces the soft sign.