We could start with...
India (one wall to keep out Bangladeshis and another to keep out jihadists from Pakistan)
EU (to keep out illegals from E. Europe)
Great Wall of China (isn't it time that old thing came down?)
Saudi Arabia (to keep out Yemenis)
Fence between North and South Korea
Fence at U.S./Mexico border (that's working really well)
And many more...
How any civilized human being could be against that fence is beyond me.
Like if people from Oakland started strapping on suicide vests and blowing themselves up in San Francisco, nobody would want to do anything about it?