Detailed Instructions: In this task, you're given passages that contain mentions of names of people, places, or things. Some of these mentions refer to the same person, place, or thing. Your job is to write questions that evaluate one's understanding of such references. Good questions are expected to link pronouns (she, her, him, his, their, etc.) or other mentions to people, places, or things to which they may refer. Do not ask questions that can be answered correctly without understanding the paragraph or having multiple answers. Avoid questions that do not link phrases referring to the same entity. For each of your questions, the answer should be one or more phrases in the paragraph, and it should be unambiguous.
Q: Passage: The mosaics of Delos are a significant body of ancient Greek mosaic art. Most of the surviving mosaics from Delos, Greece, an island in the Cyclades, date to the last half of the 2nd century BC and early 1st century BC, during the Hellenistic period and beginning of the Roman period of Greece. Hellenistic mosaics were no longer produced after roughly 69 BC, due to warfare with the Kingdom of Pontus and subsequently abrupt decline of the island's population and position as a major trading center. Among Hellenistic Greek archaeological sites, Delos contains one of the highest concentrations of surviving mosaic artworks. Approximately half of all surviving tessellated Greek mosaics from the Hellenistic period come from Delos.
The paved walkways of Delos range from simple pebble or chip-pavement constructions to elaborate mosaic floors composed of tesserae. Most motifs contain simple geometric patterns, while only a handful utilize the opus tessellatum and opus vermiculatum techniques to create lucid, naturalistic, and richly colored scenes and figures. Mosaics have been found in places of worship, public buildings, and private homes, the latter usually containing either an irregular-shaped floor plan or peristyle central courtyard.
A:
What country has one of the highest concentrations of surviving mosaic art?