Anniversary celebrations took place all over Italy. The government decided to call a national holiday to mark the special occasion. In Brussels, Italians gathered in the Parc du Cinquantenaire and for other ceremonies organised by Italian organisations.
The EU institutions also recognised Italy's landmark day. European Parliament President Jerzy Buzek stressed that the event was a European celebration and praised Italy's contribution to European integration.
Italy was one of the six founding members of the European Community after the Second World War.
The president of the European Commission, José Manuel Barroso, echoed Buzek's comments by praising Italy's cultural and historical legacy, but he also underlined that "a strong and united Europe needs a strong and united Italy".
His remark came as no surprise, since Italy is currently in the middle of one of the most divisive phases of its history.
Separatist movements are gaining ground and the government itself is dominated by a party (Lega Nord) which began its political life by explicitly calling for the secession of the wealthier north from the rest of the country.
Lega Nord's anti-national stance was blatantly confirmed during yesterday's celebrations. In addition to four ministers, just one of the right-wing party's 85 MPs was present at a solemn ceremony in the packed Italian Parliament in Rome.
Roberto Maroni, Italy's home affairs minister, tried desperately to wriggle out of attending the ceremony by arranging a last-minute meeting in Brussels with Internal Affairs EU Commissioner Cecilia Malmström to discuss the issue of immigration in the Mediterranean Sea. But eventually he had to cancel the meeting.
"He was forced to stay in Rome because the presence of the Home Affairs Minister was required during the celebrations of the 150th anniversary of Italy's unification," said an Italian government source at a meeting in Brussels.
Lega Nord strongly opposed the celebration of a national holiday to mark the anniversary.
The government, of which Lega is part, was forced to bow to Lega's demand that a specific official holiday be declared for Padania (Lega's self-proclaimed ancestral territory) in order to pass the law authorising Italy's one-off festivities.
Lega's separatist faction is currently focusing on federal reform of the Italian state to give more power and more money to regional and local authorities.
But as the North makes its voice heard in Rome, in the South anti-national stances are growing too.
One of the best-selling books in Italy in 2010 was a recent history of Southern Italy, which rebranded unification as the "annexation" of the South by Northern Italy.
Entitled "Terroni", a derogative nickname for Southern Italians, the book tells of the massacres carried out by Piedmont's army in the South in the years following unification.
The documented essay, written by the journalist Pino Aprile, cites figures asserting that the widely-held perception that Southern Italy is a poor area and an economic parasite dragging down the North is quite simply a myth.
Indeed, the Kingdom of the Two Sicilies was much richer than Piedmont at the time of unification, and since then has been systematically despoiled of its wealth and industry by invaders from the North, the author argues.
Emigration from the South started in this period, while until then only Northern Italians, especially from the Veneto (Lega's stronghold), had migrated.
The book is helping to feed a growing anti-national mood in Southern Italy, where nostalgic supporters of the former ruling French dynasty (the Bourbons) are gaining momentum, together with movements which mirror Lega Nord's positions.
Sicily, the biggest Southern Italian region, is currently governed by a party called 'Movement for Autonomies – Allies for the South'.
