New Delhi, Sept. 2 -- Supporters of President Donald Trump have floated the idea of adding his likeness to Mount Rushmore, one of the United States' most iconic monuments. The idea gained attention shortly after Trump began his second term, when Representative Anna Paulina Luna introduced a bill proposing the addition. While the legislation has not progressed in Congress, the physical feasibility of adding a fifth face presents a significant hurdle.

Experts NBC News has spoken to say Mount Rushmore simply does not have enough suitable rock for new carvings. Paul Nelson, a retired engineer who oversaw the monument's rock monitoring system, explained, "It comes down to the geology, the engineering. It just can't be done."

Gutzon Borglum, ...