The Colorado Scale Model of the Solar System is located on the campus of the University of Colorado, Boulder. It's one of the more clever ways I've seen of educating people on relative planetary sizes and distances between bodies in our solar system. The scale of this model is 1 to 10 billion.
The Sun and inner planets are located in front of the Fiske Planetarium. The Sun is about the size of a grapefruit (14 cm diameter), and planets generally are only a few millimeters in dimension, as illustrated in these plaques.
The inner planets (Mercury, Venus, Earth, Mars) are all located within a couple dozen steps of the sun. The outer planets (Jupiter, Saturn, Uranus, Neptune, Pluto) are spread much farther apart. Pluto is located about 600 meters from the Sun.
The model opened in 1987 and was refurbished in 1993. A major update is currently underway to refresh the displays, said to be completed this year (2021).
Our son, who completed his doctorate in Astrophysics at UC Boulder last year, shared this model with us while we were visiting him. He also showed us around the campus including nearby Fiske Planetarium....
I enjoyed this large copy of Earth outside the University's Geology building.