This aerial drone photo taken on Dec. 25, 2025 shows the Quancheng Park Station of Jinan Subway Line 4, in Jinan, east China's Shandong Province. China's first subway line passing through a karst spring area began operation on Saturday in Jinan, marking an engineering breakthrough that balances urban transit demands with the protection of natural water resources. Jinan Subway Line 8 and the east section of Jinan Subway Line 6 started operation on the same day, increasing the city's total rail transit mileage to 248 kilometers. (Xinhua/Zhu Zheng)