The Fourth Plinth – a rotating public art project in London’s Trafalgar Square – is celebrating its 25th year with a new installation, which was unveiled earlier today (September 18).

The 15th work to occupy the Fourth Plinth since the project was first launched in 2009, ‘Mil Veces un Instante (A Thousand Times in an Instant)’ is an original sculpture by Mexican artist Teresa Margolles. It is made up of plaster casts of the faces of 727 trans, non-binary and gender non-conforming people in Mexico and the UK. According to Margolles, the work “stands not only as a display of resilience and humanity from the trans plus/non-binary community but also as a reminder of the murders and disappearances that still occur, especially in Latin America.”

In particular, the sculpture is a tribute to one of Margolle’s friend and collaborators, a transgender woman named Karla who was murdered in Juárez, Mexico in 2015, and whose death remains unsolved. “We pay this tribute to her and to all the other people who were killed for reasons of hate. But, above all, to those who live on, to the new generations who will defend the power to freely choose to live with dignity,” Margolles said in a statement.

According to a press release issued by the Mayor of London, the arrangement of the casts references the form of a Tzompantli – “a skull rack from Mesoamerican civilisations typically used to display the remains of war captives or sacrifice victims.” As the work is exposed to the damp weather of London, it will start to age naturally and the faces it depicts will slowly fade. Working with queer community groups in Mexico City, Juárez and London, Margeles created the casts by applying plaster directly onto the faces of the people taking part. The resulting artwork is infused with their hair and skin, as well as capturing their features.

Margolles is a conceptual artist, photographer, videographer and performance artist, who started working out as a forensic pathologist. She continues to incorporate this experience into practice, which often makes use of forensic materials, such as water used to wash dead bodies or the diluted blood of victims. Her work typically explores themes of conflict, from gang violence in Mexico City to transphobic hate crimes.