Dear John Smith,

I hope this letter finds you well. I am writing to invite you to a lecture related to Chinese tea culture. The lecture will be held at the local library on Saturday afternoon at 2pm. It promises to be an interesting and informative event, and I think it would make for an excellent cultural experience for you during your visit here.

If you are interested in attending, please let me know and I can provide further details about the event. I look forward to hearing from you soon!

Warm regards,
[Your Name]