- Macron hopes to build a relationship with the new occupant of the White House.
- Nearly 11,000 police officers will be on duty, with France in its highest state of alert.
Back home, Trump on Wednesday defended his eldest son, Donald Trump Jr, praising his "transparency" for releasing an email chain about a meeting with a Russian lawyer and again decrying as a political "witch hunt" the row about whether the Kremlin helped him win the White House last November.
Macron, 39, is hoping to use the weight of history and French grandeur to charm the unpredictable Trump — six weeks after welcoming Russia's Vladimir Putin at the grandiose Palace of Versailles.
In London, Berlin, Brussels and Paris, European leaders are wondering how best to handle the US president, whose nationalist "America First" agenda has upended transatlantic relations.
Macron hopes to build a relationship with the new occupant of the White House that might enable him to influence US policy or, at the least, help avoid serious strains between the EU and Washington.
There are already tensions over climate change and trade, while Trump was openly critical of the EU last year and snubbed a handshake with German Chancellor Angela Merkel during their first meeting in March.
"It's very difficult to play chess with a man whose strategy is a complete mystery and whose only consistency is his pursuit of American national interest," foreign affairs expert Bertrand Badie of Sciences
Po university in Paris told AFP. "To imagine that you might change his mind on something is simply mad."
Talks between the two leaders are expected to focus on joint efforts to combat the Islamic State group in Iraq and Syria, where American and French troops are in action side-by-side.
The two leaders will dine together at the Jules Verne restaurant up the Eiffel Tower, enjoying stunning views of the French capital along with their wives Melania and Brigitte.
Trump and Macron appear to have little in common, with their views at odds on everything from globalisation to immigration.
Macron was even described as the "anti-Trump" during his run for the French presidency this year.
As well as a huge generational gap — Trump at 71 is almost twice Macron's age — there is scant evidence of any overlap of interests in their personal lives.