他想来北京看长城：He wants to come to Beijing to see the Great Wall
想来北京看长城 - I want to come to Beijing to visit the Great Wall Of China (注：语法不通)
你是想说：”想来北京看长城“ 还是 “想去北京看长城”?已经到了北京?一直都在北京?刚抵达北京?
如果情况是“已经来到北京.来看看长城”：I came to Beijing to visit The Great Wall of China.
如果情况是“人不在北京.想去北京看长城”：I want to go to Beijing to visit The Great Wall of China.