开封

Capital of seven dynasties, most famously the Northern Song (960-1127), when it was called 东京 (Dongjing) - possibly the largest city in the world at the time. The famous scroll 《清明上河图》 (Along the River During Qingming) depicts Song-era Kaifeng at its peak.

mistakes

As a place name, 开封 is read Kāifēng (both first tone). As a common verb 开封 (kāifēng) means "to unseal / open a sealed envelope" - same characters, different context.