The monolith in Arthur Clark's movie 2001 was sent to 'reengineer' humanity's ancestors so they could ultimately evolve into a space traveling race. There were several monoliths.
The first one induced the propensity to use tools. After such an ability came about it fast forwards to the future where humanity has a space station and the ability to easily travel to the moon. That's where a second, larger monolith is discovered.
When the lunar monolith is discovered it sends a message to the planet Jupiter as an apparent bait for further space exploration. Inevitably a spaceship is sent to Jupiter (Saturn in the book) to investigate.
David Bowman is the astronaut on the ship who makes contact (after being temporarily sidetracked by a psychotic computer) with a third and largest monolith. That monolith is a space portal that sends Bowman to another location in the galaxy.
The last part of the movie is semi-metaphoric but it has Bowman in custody, well taken care of in a hotel like environment, for the rest of his life until he's just about to die. That's when a small monolith appears in front of his deathbed and sends him back to Earth reborn as an infant god.
It comes down to this. An extraterrestrial race wanted humanity to evolve further so that they could be gods.
Not quite like anything the Bitchtower does.