A shrine was erected on the site in 1983 with a monument created by the sculptor Mastroianni. Near the Rio Secco stream, there is the iron cross at the exact site of the massacre. Three miraculously survived, who were eyewitnesses to the massacre.

The Massacre of Collelungo, Cardito di Vallerotonda hamlet, is one of the most brutal carried out by the Germans while on the Gustav Line. The place where civilians had sheltered from the harshness of winter was made up of ravines and caves, in which families had found refuge. The civilians were joined a few days before the massacre by four straggling Italian soldiers, who were also killed and whose names are still unknown.

The place was located in a gorge near the Rio Secco, close to the Mainarde Mountains, where the troops of the French Expeditionary Corps, particularly Moroccans, had been trying for days to break through the German lines to implement the plan devised by General Alphonse Juin, called 'the Atina manoeuvre', which was to break through in the direction of the Comino Valley, bypassing the fortified German defences at Cassino. Still today, the reason for the massacre and the German unit that carried it out remains unclear. The sites were occupied by the 100 Gebjrsjager Regiment of the 5th Mountain Division, but soldiers from the 115th Panzer Grenadier Regiment of the 15th Panzer Division had also been sent for reinforcement during those hours. The survivors were only able to recount the excruciating phases of the massacre, carried out without any mercy or hesitation by the Germans.

The corpses were covered as best they could with branches and leaves and abandoned on site. They were recovered a long time later. The Collelungo memorial, embedded in the Mainarde mountains, in the beech forests, is a unique natural site, full of a great sense of compassion for those who lost their lives there.

Historical associations visit the site of the massacre every year on 28 December, whereas the official celebration by the Vallerotonda municipality takes place on the first Sunday in August.