American GIs brought bubble gum, big bands and even the `national pastime' - baseball - to Belfast during wartime, archive images show.
PRONI's document of the month for August is a series of merged images of Ravenhill.
The series of photographs, featuring baseball, American football and rugby have been merged with pictures of the same locations in the present day.
US troops began to arrive in Northern Ireland in the early 1940s. By the summer of 1942, more than 41,205 American military personnel were stationed across the north.
A 12-team league, which featured teams with names including the New York Eagles, Medical Corps Pill Rollers and Californian Eagles, was based in Belfast and staged its opening day at Ravenhill.
The original images and the merged images are available to view in PRONI. These photographs are the latest addition to the growing online archive of images, which includes thousands of photos from several collections.
The newly-published photos also show American football being played at the famous venue. While the home of Ulster Rugby, Ravenhill has hosted various other sports over the years.
Last year, gaelic football returned to Ravenhill for the first time in more than 90 years for a game to honour former Antrim captain Anto Finnegan and raise awareness of Motor Neurone Disease.
Shane Logan from Ulster Rugby revealed that before 1924, and Ulster's first game against Leinster, Ravenhill was a GAA ground.
Garreth Montgomery from PRONI said the new images caught his attention as he thought it was very unusual to see American football and baseball being played in Belfast.
While the Belfast Northstars baseball club has been in existence for almost 20 years, the sport has taken off in the city this year with the establishment of two more teams - the Hornets and Bucs.
There is now, for the first time, a northern division of Baseball Ireland, a purpose-built baseball facility is taking shape at Hydebank, and last month Belfast hosted its first ever international baseball tournament.
Mr Montgomery said the PRONI images showed how much Ravenhill had changed and how the ground was used during the war years by GIs.
"I am always on the lookout for interesting old photographs in our collections that could be merged with contemporary digital shots taken in the same location today. These merges have proved hugely popular on our Flickr stream and as a means to highlight the various collections we hold in PRONI," he said.
"In doing so, I came across these rare shots of GIs playing baseball and American football at the ground in the early 1940s. Being a regular at Kingspan Stadium and following Ulster Rugby, I thought it would be interesting to try and merge these old shots with ones taken in the same location 70 years later during PRO12 league matches."
IRFU (Ulster Branch) President Bobby Stewart added: "These images are remarkable as they really emphasise how much Kingspan Stadium has evolved over the years, particularly since the redevelopment work was completed in 2014. The stadium has hosted many high profile sporting events, not only in rugby but in other sports such as soccer and Gaelic football, as well as the American sports which are highlighted in these images."
