Barcelona's Montjuïc is a broad shallow hill with a relatively flat top overlooking the harbour, to the southwest of the city centre. The eastern side of the hill is almost a sheer cliff, giving it a commanding view over the city's harbour immediately below. The top of the hill (a height of 184.8 m) was the site of several fortifications, the latest of which (the Castle of Montjuïc) remains today. The fortress largely dates from the 17th century, with 18th-century additions. In 1842, the garrison (loyal to the Madrid government) shelled parts of the city. It served as a prison, often holding political prisoners, until the time of General Franco. The castle was also the site of numerous executions. In 1897, an incident popularly known as Els processos de Montjuïc prompted the execution of anarchist supporters, which then led to a severe repression of the struggle for workers' rights. On different occasions during the Spanish Civil War, both Nationalists and Republicans were executed there, each at the time when the site was held by their opponents. The Catalan nationalist leader Lluís Companys was also executed there in 1940, having been extradited to the Franco government by the Nazis.