Between the Plaza del Maqués de la cadena and streets Sancho Ramirez and Ramon y Cajal we find a stone tower built on the blocks that formerly occupied the Royal Palace. Today is the headquarters of the Working Community of the Pyrenees. Throughout the time the tower has been known as Torre del Merino, Tower Prison, Clock Tower and Tower of the chain.

Is an example of Gothic civil architecture and was built around the year 1445 as a private residence, in the same area where had been the palace of the King of Aragon which was destroyed by the fire that devastated the city in 1395.