We will be travelling to HK on July and would like to visit Shenzhen for a daytour only.
WE would like to visit the "Windows of the World". I heard if you travel in a group of 3, the visa is free?
Not so keen about this info though. Can anyone suggest where to get a Shenzhen daytour from HK and more or less how much that would cost? Is there a need for a Shenzhen visa for a group of 3?

Would appreciate getting some feedback. Thanks.