If your 100 year mark is accurate, why is the Pantheon still standing? It’s approaching 1,900 years.
You are an engineer and you are asking me?
Does the dome hold back 16 million acre feet of water? Does the dome take a constant traffic load including vibrations? Is the dome exposed to hot and cold extremes?
The dome material actually consists of lite weight aggregate which is supported by granite (stone) columns but of course you already knew that. Many (older) Roman roads and aqueducts still standing and some still in use.
Go back your trains.