The current Manchester United boss moved to Camp Nou in 1997, a year after leading a young Ajax side the Champions League title.
However, Gerard van der Lem, who had been Van Gaal’s right-hand man during his time in Amsterdam, has revealed that his former boss could have easily ended up at the Santiago Bernabeu instead.
"Real Madrid and Barcelona both wanted Van Gaal in 1997," he told De Telegraaf.
"He asked me: 'What do you want?' I said that I preferred Barcelona... Madrid is right in the middle of Spain and is always incredibly hot in the summer and very cold in the winter.
"Barcelona has a more pleasant climate, seemed like a nicer city and I enjoy the sea.
"Louis then told me that he would open talks with Barcelona."
Van Gaal succeeded Bobby Robson as Barcelona boss, with the Catalans deciding to return to their Dutch roots in an attempt to rekindle the glory days of Johan Cruyff’s 'Dream Team'.
The 63-year-old claimed two league titles during his first three-year stay in Spain before returning for an ill-fated second spell in 2002, after two years with the Dutch national team.