Figured Out?

Grand Church of the Winter Palace. As the name implies, it's a church built in the Winter Palace.

The whole Ruthenian Royal Family entered the cathedral and Alexander's mouth dropped in wonder the moment his eyes set upon the interior design.

Sunlight streamed in on both sides of the gilded walls, lighting up the hall with an ethereal glow, the walls were adorned with gilded intricate patterns, a frescoed ceiling, and last but not least, the altar itself. 

So this is the Church of the Winter Palace huh? Alexander thought to himself, he must admit, it was his first time visiting here as Thomas—

"Alexander, are you visiting this place every Sunday?" 

Natalya's sudden question made him jump out of his thoughts. He turned towards his sister who was smiling at him innocently.

Alexander sifted through his memories, searching through thousands of memories where he visited the place. An answer appeared abruptly.