How do historians know the Romans borrowed the use of arches and columns from the Greeks?

Answer 1

Regarding the arches, it is thought that monumental arches were invented by the Etruscans, not the Greeks. The Romans were the first to fully appreciate the potential of the simple (barrel) arch and the vaulted arch (or vault). The latter consists of two to four intersecting arches. The arch has a great load-bearing capacity and the structure of the vault is well suited for building large roofs. The Romans were the first to make large scale use of the arch and vault. These two and the large scale use of (Roman) concrete were the three key elements of what historians have called the Roman Architectural Revolution or Concrete Revolution. Concrete was a tough material and was much easier to lay (Roman concrete was as strong as modern concrete, but was less fluid and had to be layered by hand). Building with concrete did not require skilled labour and was quicker and easier that building elaborate walls with stone blocks. However, the Romans also built stone aches. These three elements enabled the Romans to go beyond the Greek post-and-lintel methods of construction.

Regarding the columns, it is known that the Romans borrowed their construction from the Greeks because they also adopted the three Greek orders (styles) for building columns: the Doric, Ionian and Corinthian orders. The Romans also introduced the Composite order, which combined elements of two of the mentioned orders.