Zaragoza is a beautiful city with an old town that has a mix of Gothic and Islamic architecture. It was originally founded by Ancient Iberians and then replaced by the Roman city Caesaraugusta a few decades BC. There is a statue of Caesar Augustus near the Roman Walls in the Old Town (Casco Antiguo).
Zaragoza's main tourist attraction is the amazing and massive Pilar Cathedral, Basílica de Nuestra Señora del Pilar, that is located on the Ebro River which runs through the city. The cathedral is located in the Old Town in the Plaza del Pilar next to the Fuente de la Hispanidad and the Iglesia de San Juan de los Panetes which has a visibly leaning tower. The cathedral is so big that it's hard to capture in one photo from the plaza. The best views of it are from across the river along walking path and from both bridges, the Puente de Piedra and the more modern Puente de Santiago.
Another popular tourist site is the Palacio de la Aljafería located a few blocks from the river and outside of the Old Town. It is a fortified medieval Islamic palace built in the 11th century during the Muslim conquest and 700 year occupation of the Iberian Peninsula.