From 2023 on, Tang and the play's creative team immersed themselves in extensive research, including the study of architectural history, wartime Beijing, and the technical discipline of surveying.

They traveled to Tianjin University to trace the legacy of the Society for Research in Chinese Architecture, one of the earliest and most important academic institutions devoted to the systematic study and documentation of traditional Chinese architecture in the 20th century. They examined archival materials, practiced field measurements, and conducted in-depth research in the Forbidden City, consulting contemporary experts to anchor the play in professional, historical reality.

"In the play, the swift becomes a metaphor for endurance and faith," says director Fang Xu, who is known for his adaptations of Lao She's works, including Rickshaw Boy and Niu Tianci. On a more poetic and symbolic level, he says, the image of the Beijing swift runs through the entire production.

Although the drama still carries a strong sense of "Beijing flavor", Fang notes, it does so in an alternative way. "One of our biggest challenges was finding the balance between professional architectural details and dramatic storytelling," he says.

"Ancient buildings are enormous. Even the roof ornaments of the Hall of Supreme Harmony are nearly three meters tall, making the human figure look small by comparison. This contrast is visually powerful, but it is impossible to re-create such a true-to-life scale on a theater stage," Fang explains. "The question of where reality ends and poetry begins became part of the production's core language."

Guo Shuojie, who plays protagonist Zhang Di, followed the production team to conduct research at Tianjin University and the Forbidden City. There, he learned that surveying ancient buildings often means crawling into narrow spaces beneath old rooftops — places that never see daylight and are filled with dust, mold, and even the smell of bat droppings, making it almost impossible to stay for long.

"An expert told me that he often finds the names of craftsmen and the dates of their work written on old beams," Guo says. "At that moment, it felt like he was meeting those ancient builders across time. That's when I began to understand the belief that holds my character together."