Sagittarius A*
Claim in the list: At the center of the Milky Way lies the supermassive black hole Sagittarius A*, with a mass of about four million Suns.
Verification: Confirmed. Sagittarius A* (Sgr A*) is a compact radio source at the Milky Way’s dynamical center associated with a supermassive black hole. Orbits of nearby stars and Event Horizon Telescope observations are consistent with a mass of about four million solar masses. It lies roughly 26,000–27,000 light-years from the Solar System.
Conclusion: The Milky Way’s center contains the supermassive black hole Sgr A*, with a mass of approximately four million Suns.