This is the 8253rd most frequent Russian word.
мариинский
Relating to Saint Mary or the Mariinsky Theater (in St. Petersburg).
In this sentence, 'мариинский' is used as an adjective to describe the theatre named after Maria, which is a cultural institution in St. Petersburg.
Мариинский театр является выдающейся культурной достопримечательностью Санкт-Петербурга.
The Mariinsky Theatre is an outstanding cultural landmark of St. Petersburg.
Here, 'мариинской' is the genitive form of the adjective referring to a system related to Maria or a place named after her.
Правительство утвердило финансирование мариинской системы водоснабжения.
The government approved the funding for the Mariinsky water supply system.
In this instance, 'мариинская' is an adjective form used to denote the hospital named after Maria.