Lagos is one of the larger cities in the southern Algarve region of Portugal. While its history dates back to the 13th century and many excursions by Henry the Navigator it i snow primarily a fishing village and more predominantly a tourist attraction for beach-going Europeans.
The city contains miles of beaches with the beaches on the western end being the most well known for the steep cliffs that decorate them. In particular Paria Dom Ana and Praia do Camilo are well worth visits. They are slightly secluded from the outside world by their cliffs while Meia Praia and Praia San Roque to the East of the city has much more room for bathing but is less scenic.
Lagos does not have direct train routes to Lisboa, but many direct buses run here. If taking the train then you will need to take a train towards Faro and change at Tunes which will take a total of 4 hours. In addition, trains run directly to Faro almost every hour.