Earlier she had unbelievably survived London bridge attack while travelling on the tube when it was put on lockdown in June and was in Paris' Notre-Dame Cathedral at the time when a policeman was wounded outside the grand church in a terrorist attack.
Spanish airport company AENA fell 2 percent after Thursday's attack, in which a suspected Islamist militant drove a van into crowds in central Barcelona, killing 13 people.
In as many months during Julia's trip around Europe, she was lucky to escape unharmed after finding herself caught up in terror attacks in three different countries.
World leaders are standing in solidarity with Barcelona following the deadly van attack inside the city's major tourism centre on Thursday, August 17.
"We were looking at about 200 people crowded out in the square. suddenly everyone outside just started screaming and everyone turned at the same time".
A counter-terrorism strategy document will be given to Australian businesses and councils, outlining ways to prevent vehicle attacks similar to those seen in Barcelona and Nice, reports say.
She said on 9News: "We didn't see the van".
"People were literally pushing to get into the store off the street. we were genuinely terrified".
Monaco and her friends were corralled into an Urban Outfitters store and told to lie face down on the floor away from the windows.
Monaco went on to talk of the fear she and her fellow shoppers felt as they watched people rush out of the mall and then the fury that engulfed her as she had to contend with the fact that her life could be threatened by terrorists when all she wanted to do was enjoy a holiday.
"I feel a bit rattled, it's not how I really expected today to go", she told Melbourne radio 3AW.
"I feel like I want to stay here and not let "them" - whoever "they" may be - win and I'm gunna see what I came here to see", she added.
Prime Minister Malcolm Turnbull is set to reveal a plan to stop vehicle-based terror attacks in Australia.
"There is a little Australian boy, whose mother was badly injured and is in hospital, and he is lost - missing in Barcelona", Turnbull said.