Those in Brussels will be open later this month (28 May).
The move was described by Parliament as a "unique opportunity to discover the diversity of Europe in a fun and family-friendly atmosphere."
The events mark the anniversary of the Schuman Declaration of 9 May 1950, which is regarded as the key event in the creation of a united Europe.
As well as commemorating a landmark, Europe Day, said a parliamentary spokesman, is an opportunity to "further promote transparency and encourage closer ties between the European Union and its citizens."
Opening their doors will, he said, give the citizens the chance to discover their daily work of MEPs and the institution.
The central theme of the 24th edition of the Open Days event will be the EU motto 'United in diversity'.
The spokesman said; "Europe is a multi-faceted melting-pot of languages, cultures, religions and political opinions, and this diverse identity is reflected in its fundamental values and governing institutions."
On Sunday, Open Days will be officially launched by Parliament Vice President Rainer Wieland, a German EPP member, followed by a public debate in the chamber with MEPs on the theme of "United in Diversity".
Visitors will be able to take a signposted tour explaining the Parliament's role and powers.
Meanwhile, in Brussels on 28 May, there will be a debate with MEPs based on Mahatma Ghandi's quote "Our ability to reach unity in diversity will be the beauty and the test of our civilisation."
The Parlamentarium, Parliament's visitor centre, will host the photo exhibition, 'Displaced', with photographs of women refugees and asylum seekers.
Visits to the plenary chamber, including a briefing about the role and the duties of the Parliament, will also be organised.