Movie about mom and two kids who move in with grandpa on a mountain

Ok so I’m trying to find a movie about two kids who move with their mom to their grandpas house on a mountain.

This detail is fuzzy so I don’t know if it was actually in the movie or not but I think there was a guy trying to by the land because he knew something was there.

The kids eventually find a way into the mountain and find like an ancient civilization or the ruins of like an Aztec city or something inside of the mountain.

Whenever I see the movie race to witch mountain I always think of this movie, something about the title race to witch mountain sparks thoughts of this movie. I’ve tried everything and I just want to make sure it wasn’t a fever dream, y’know?