There are several mysterious Roman and ancient ruins in Portugal that are worth exploring. Here are some of them:

Conimbriga: This is one of the largest Roman settlements in Portugal, located near Coimbra. The site includes a forum, thermal baths, a large amphitheater, and several well-preserved mosaics.

Roman Temple of Évora: This is a well-preserved Roman temple located in the city of Évora. The temple is dedicated to Augustus and is one of the most important Roman landmarks in Portugal.

Balsa: This is an ancient Roman fishing village located on the coast near Tavira. The site includes several well-preserved fish salting tanks and other structures related to the fishing industry.

Milreu: This is a Roman villa located near Estói. The site includes several well-preserved mosaics and frescoes, as well as a bath complex and a temple dedicated to the goddess Venus.

Mirobriga: This is a Roman city located near Santiago do Cacém. The site includes a forum, thermal baths, and several other structures, including a well-preserved aqueduct.

Citânia de Briteiros - This Iron Age hill fort is located near Guimarães and dates back to the 3rd century BC. The ruins include stone walls, houses, and a large central plaza.

These are just a few of the many mysterious Roman and ancient ruins in Portugal. Each one offers a unique glimpse into the past and is well worth a visit for anyone interested in history and archaeology.