I’m writing to invite you to the lecture on the Great Wall, which will be made by Professor Wang from Tsinghua University. The lecture will focus on the reasons why the Great Wall was built and the construction features as well. It will be held in Room 102 on the first floor of No.3 Teaching Building on May 7th this Saturday. As far as I know, you like the traditional construction of China, so I think you will enjoy it.The lecture will last three hours from 8 to 11 am. Questions are welcome after the lecture is given. I will be glad if you come.Looking forward to your reply.