This bill proposes to amend the Antiquities Act to significantly increase congressional oversight over the designation of national monuments by the President. It introduces a critical limitation, making such designations effective only until the earlier of six months after establishment or the last day of the current Congress , unless extended by statute. This means presidential monument designations would no longer be permanent without legislative approval, requiring Congress to act for their continuation. Furthermore, if a designation is not extended or is rejected by statute, the specific land or property involved would be subject to a 25-year moratorium , prohibiting its inclusion in any future national monument designation under the Act.