Symbols are an evolving library of information that pulls us together into the same conversation. Many symbols go beyond religious and cultural markers that are recognized by all, while some need to be learned before they are used and understood.
The key ingredient in a symbol is meaning. Anything can be a symbol, if it has meaning and sufficient recognition or use, it will eventually make it into the library of symbols of a religion, nation, the western or the eastern world, or humanity.
Neoclassical architecture as it is present in North America and especially United States has been associated with many meanings out of which in the case of Lincoln Memorial is democracy.