|Baidu's 2013 May 1 Doodle shows people|
building a wall.
According to Baidu's "Encyclopedia" (百科 “Baike” a wikipedia service) entry for "May 1" (五一):
On July 14, 1889, at a meeting of representatives of various Marxist and Socialist countries was convened in Paris, France. At this meeting, the French representatives proposed: designate May 1, 1886, the day that American workers struggled for an eight hour work day, International Proletariat Day.These screenshots, taken on May 1, 2013, show that Baidu bans users from establishing forums on its PostBar (Tieba 贴吧) service on the following topics: Marx (马克思), Socialism (社会主义), Proletariat (无产阶级), Workers (工人), Labor Unions (工会), and Strikes (罢工).