Unfortunately, invading British and French expeditionary forces stole or smuggled cultural relics from the Summer Palace in 1860.

As a result, just dozens of his works survived and are housed in the Palace Museum in Beijing and the Palace Museum in Taipei.

In Attiret's long letter, he wrote, "Since my residence in China, my eyes and taste have grown a little Chinese." The letter was translated into English and published in 1752, and had great influence in Europe.

Their letters, notes, paintings and books are precious historical materials helping scholars and historians today to glimpse into the palace hundreds of years ago, architectural historian Yang Naiji tells the Palace Museum's in-house magazine.

The Forbidden City was renamed the Palace Museum in 1925, one year after the last emperor, Puyi, went into exile. It became a UNESCO World Heritage Site in 1987, welcoming millions of tourists from home and abroad. The museum received a record 19 million visitors last year.

"From the Forbidden City to the Palace Museum, the palace complex has played, still plays and will play a vital role in communication between the East and the West," Zhu says.