Meanwhile while leftists are throwing a fit over President Trump's proposed border wall with Mexico, they couldn't care less about Turkey's new massive 764-kilometer border wall with Syria paid for with European Union funds.
http://www.informationliberation.com/?id=58567

or elsewhere in Europe:
Bulgaria
Slovenia
Hungary
Macedonia
Austria
France

Of Course we all know the Great Wall of China and Hadrians Wall were merely built to entertain tourists thousands of years later, and Offa's dyke was built to enable the confiscation of bows and arrows off the wayward welsh
https://www.indy100.com/article/a-map-of-the-six-european-countries-who-have-built-a-wall-to-stop-migrants-7320271

http://theconversation.com/europes-wall-against-african-migrants-is-almost-complete-76758