Wearing masks and sunglasses, they recorded themselves picking locks in a condominium and climbing to its roof, which looks to be around 40 storeys high.
The two men, who look like they are in their early 20s, then sat precariously on the ledge of the building to take photographs with selfie sticks.
The video was posted on YouTube on March 4, but it only made its rounds yesterday, when it was picked up by citizen journalism site Stomp.
It is not known when it was recorded.
At one point, the duo can be seen picking a lock on the ground floor with a Swiss Army knife to access a stairwell.
They also managed to enter a private pool, believed to belong to a penthouse unit.
The building in question is Soleil@ Sinaran in Novena.
It overlooks Tan Tock Seng Hospital and Oasia Hotel, both of which can be seen in the video.
Calling themselves the Urban Summit, the pair claims to "explore closed-off urban areas" and that the video shows one of their first climbs.
"We take precautions and measures to not damage the property and leave everything as we found it," said the video description.
They could be breaking the law, especially if they are not residents of the condominium, says lawyer Terence Seah.
Says Mr Seah: "Just stepping into a condominium itself without permission is trespassing.
"Tampering with the lock with a jack knife - that can be considered as mischief. They could even be charged with vandalism, which carries mandatory caning on top of jail time."
But the condominium management might also find itself in legal trouble if the two intruders injure themselves.
The management could not be reached for comment last night.
This article was first published on March 22, 2015.
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