## 1 Introduction  
The polychromy of ancient Greek sculptures has been the subject of studies for over a century, as remains of painted decorations were already documented during the archaeological excavation of the Athenian Acropolis at the end of 19 th century [1]. Watercolor illustrations of colored sculptures and architectural elements were painted immediately after their discovery, in an attempt to \"photograph\" their ephemeral appearance due to the acceleration of degradation processes. Polychromy was extensively used on stone sculptures [2; 3; 4], architectural elements [5; 6], and on terracotta figurines [7; 8; 9] as a constituent component of three-dimensional artworks due to the symbolic, communicative, and aesthetic use of color [10]. After the Second World War, the debate about the polychromy of ancient sculptures attracted scholars from many disciplines, whose research has been devoted to the reconstruction of the original appearance of artefacts through investigation of their surfaces and the analysis of pigment remains since then [3; 11; 12; 13; 14; 15; 16; 17; 18; 19; 20; 21; 22; 23; 24; 25; 26]. Advances in technical photography strongly enhanced out capacity to visualize residual traces of pigments, becoming crucial in creating three-dimensional, physical reconstructions of painted sculptures [1; 12; 13]. The Metropolitan Museum of Art (The Met) has been part of the conversation about ancient polychromy since the beginning of the 20 th century, when [PERSON] Classical scholar author of an influential article on the subject in 1892, encouraged the acquisition of sculptures showing residual paint traces, to convey insight into their original appearance, during his tenure as The Met's director [27]. Renowned classical archaeologist and former Met curator [PERSON] made significant contributions to the field through careful analyses of many works in the collection [28; 29]. The Met contributed to the ongoing conversation about polychromy with the exhibition _Chroma: Ancient Sculpture in Color_, opened in July 2022. During the exhibition preparation, an ambitious multidisciplinary project was initiated to investigate the extant and original polychromy of ancient sculptures within the Museum's Greek and Roman collections. Several museum departments were involved in the project, including Greek and Roman Art, Objects Conservation, Imaging, and Scientific Research. Among the several studied sculptures, an Attic funerary stele carved from Parian marble, which features a youth and a young girl, its capital and finial in the form of a sphinx (11.185a-d, f, g, x, Figure 1), received special attention, not only because it is one of the most extensively painted monuments in the Greek and Roman collections, but also because the exhibition included a reconstruction of the sphinx finial realized by [PERSON], Head of the Department of Antiquities at the Liebigehaus Skulpturensammlung in Frankfurt, and [PERSON]. Figure 1: Marble stele with a youth and little girl, and a capital and finial in the form of a sphinx (11.185a–d, f, g, x). (**A**) Overall view; (**B**) Marble capital and sphinx. Greek, Attic, ca. 530 BCE. The Metropolitan Museum of Art, New York. This unique funerary monument, extensively described in [30], is more than 4 m high (about 14 feet) and is displayed in two separate set ups: the stele on one side, and the sphinx with its capital in a display case next to the stele (Figure 1). Traces of original color were documented in previous studies [28; 29] based on visual observation, but not supported by scientific analyses. With the main goal of understanding the paint materials and uses on funerary monuments, the identification and distribution of pigments was achieved using a suite of non-invasive and micro-invasive scientific techniques. The technical and scientific investigation of the Attic grave stele presented analytical challenges that well exemplify the constraints often encountered when working on objects belonging to museum collections.