Its full name is the Memorial del Detenido Desaparecido y del Ejecutado Político (memorial for detained-disappeared people and those executed for political reasons).
At the side of the monument itself are niches, some of them empty and some with victims' names and flowers.
The main monument itself is a large, stone wall with a list of victims carved into it. As with other such walls, the effect is largely due to the sheer number of names. In the very centre is president Salvador Allende.
The memorial is topped with a quotation from Chilean poet Raúl Zurita, who you can hear reading here.
I always really like seeing a memorial used, actually part of the fabric of life. In this case, at the bottom of the memorial are many notes, photos, little plaques, flowers, and so on. It's a sombre site but then, it is in a graveyard. The important thing is these victims did not previously have anywhere where their families could go to mourn them and to mark their lives, and now they do, and they are acknowledged in the chief cemetery of the capital city as being part of the country's history.