This is the depository that Moron described in Mormon 6:6.
It was likewise stated to me by David Whitmer in the year 1877 that Oliver Cowdery told him that the Prophet Joseph and himself had seen this room and that it was filled with treasure, and on a table therein were the breastplate and the sword of Laban, as well as the portion of gold plates not yet translated, and that these plates were bound by three small gold rings, and would also be translated, as was the first portion in the days of Joseph. When they are translated much useful information will be brought to light.
You can read it here:
The existence of the depository of Nephite records in the New York Cumorah was attested by several of Joseph's contemporaries.
Yet we never hears about it in books such as Saints or in any modern Church manuals, artwork, etc.
Why is that?
Because of M2C.
A New York depository contradicts M2C because the M2C intellectuals and their followers believe the "real" Cumorah is in southern Mexico.
For that reason, the M2C intellectuals claim David Whitmer was wrong. Brigham Young was wrong. Heber C. Kimball was wrong. Wilford Woodruff was wrong. Ultimately, they claim Oliver Cowdery was wrong.
There's a fun new film coming out about the Witnesses.
It is being produced by M2C intellectuals. It will be fascinating to see how they treat this topic.