Moving farther inland, Aragon is an interesting place with lots of varying topography: lots of valleys and mountains farther south but flatter areas in central and northern Aragon. Then you hit the Pyrenees.
M experiences here range from Loarre Castle and Roda de Isábena in the north to Teruel in the south. I generally went by car, which took several hours from the Barcelona area. There is one large city, which is the capital: Zaragoza.
Historically Aragon was also the seat of the Kingdom of Aragon. Remember Ferdinand and Isabella, the monarchy who finished the Reconquista and financed Christopher Columbus? Ferdinand was Aragonese and he married Isabella of Castille, ruling as joint monarchs. This eventually led to the foundation of the modern country of Spain. This was the seat where his family ruled this region for hundreds of years.
Today there are some differences between Aragon and the rest of Spain, such as the local language. There are still some speakers of Aragonese, which has similarities to Catalan and Spanish but is distinct from both. It has slowly been replaced over the past several hundred years and suffered under the dictatorship. As a result, even though it can be used nowadays, it is estimated that only approximately 12,000 people speak it; many people consider it a dialect of Castillian Spanish rather than a distinct language.
If you are looking to explore this community, I would definitely recommend renting a car. There are some places you can go using the buses but there are many more without public transport, so you will find that it is easier travelling under your own power. Depending on where you are, you may find that it is very rural. This may mean that you can’t find many places to buy food (e.g. grocery stores) or that they keep to very rural hours, meaning they close in the afternoon. I would recommend having some non-perishable food with you in case you get into a situation where you can’t get back to civilisation for a certain time.