From the looks on their faces, it seems like they've just been reunited with a long-lost friend. As it turns out, they were: the outside world filled with daylight to greet them.

A group of chimpanzees who have been locked in cages for medical testing, and have been injected with HIV and hepatitis, were released into the daylight for the first time in 30 years, The Daily Mail reported.

For 14 years, there has been an ongoing battle to release the apes from captivity after being taken from their mothers shortly after their births and brought to a research facility in Austria. Though testing on the apes ended in 1997, after the pharmaceutical company behind the research was sold and the apes sent to a fair, reintroducing them into the outside world turned out to be a difficult task.

To readjust the apes to the great outdoors, it took their keeps more than a decade -- implementing careful techniques that slowly made them comfortable beyond their four walls.

The footage, initially broadcast by RTL, a German television station on Sept. 4, shows two adult chimps staring in wonder at the grassy plains that lie before them. After a brief look-around, the first chimp turns around and hugs an ape behind him. And then they both glee out at their newfound freedom.

The chimps are incredibly happy, said keeper Renate Foidl. This is amazing. I have been waiting for this moment so long.

The lab chimps are now at the Gut Aiderbichl Animal Sanctuary, near Salzburg, Austria.