Expo2015 was a Universal Exposition hosted by Milan, Italy (https://goo.gl/iRi7Yf). It opened on May 1 at 10:00 and closed on October 31. Milan hosted an exposition for the second time; the first was the 1906 Milan International. The data set collection contains all conversations about #Expo2015 collected between 'April 23 2015' and 'November 13 2015' (1,437,301 Tweets by 218,641 users). Being the first social media Expo the attached archive aims to show the debate through 7 months of conversations of events, protests, finances, media, marketing and politics related with #Expo2015. Presence of bot-repeaters and minor comprop. Previously held in Shanghai, China 2010, next one in Dubai-UAE 2020. More info at Oohmm (src: @remagio @Oohmminfo https://oohmm.info/about).