SCP–087 is a Euclid–class item of the SCP Foundation and one of the franchise's most popular entities. Located on an unknown (censored) school (?) campus, it consists of an extremely long series of staircases that goes deeper than should be physically possible for the entity's geographic location, and the mysterious monster that lurks at the bottom, known as SCP–087–1. The cries of a suffering child can be heard deep below while on the stairs, though no matter how deep one goes they never encounter the child nor do they even get distinguishably closer to it, so the "child" is likely just a trap created by the monster, which appears as a featureless white face that generates intense fear in all those who see it.
SCP–087 is particularly popular due to a fan game based on it, from which the image for this page is taken, as it provides a full model for the monster.
"His Kind Eyes"
On the SCP website, a story entitled "His Kind Eyes" describe the thoughts of a (presumably) tennage girl, who seems to have broken her legs, and is at the bottom of the staircase. She is accompinied by 087-1, who befriends her and tries to help her escape. Soon, the D-Class start to come in, and everytime the girl, using her arms, tried to climb up the stairs, while 087-1 went ahead of her to try and get them to help, which only resulted in the first two to flee, and the third to shock herself into a coma. The fourth expendition (which you cannot view on 087's page, as it is redacted) involved the MTF squad coming down, which 087-1 was forced to kill, as they were tyring to kill them. Finally, the girl reached the top, only to find that the Foundation has locked up the door forever, after 4 failed expenditions. The girl then wept as she was to be trapped forever, but was comforted by the fact she was forever with 087-1. The girl still atempted to escape, tapping on the door, but instead of opening the door up, the Foundation sealed the door with industrial padding, apparently deriving it of oxygen. The tapping had stopped from that point on.