The Altar of Hieron is a monumental grand altar in the ancient quarter of Neapolis in Syracuse. It was built in the Hellenistic period by King Hiero II and is the largest altar known from antiquity.
The structure is aligned roughly north-north-west to south-east-east, and is located in the Neapolis. Almost nothing except the foundations of the structure survive today. The structure was partly built from masonry blocks and partially carved from the living bedrock. The altar itself is 20.85 metres wide and 196 metres long (exactly one Doric stade). This makes it the largest altar known from the ancient world.
The altar is mentioned by Diodorus Siculus, who attributes its construction to Hiero II. Stylistic analysis of the sculptural fragments from the altar confirms this, showing that they were made at the same time as the third phase of the nearby Greek theatre, which belongs after 235 BC. The votive deposit in the natural grotto under the eastern side of the altar shows that the area was already a sacred site in the Archaic period, not long after the city of Syracuse was established.
References:The Roman Theatre of Mérida is a construction promoted by the consul Vipsanius Agrippa in the Roman city of Emerita Augusta, capital of Lusitania (current Mérida). It was constructed in the years 16 to 15 BCE. One of the most famous and visited landmarks in Spain, the Roman Theatre of Mérida is regarded as a Spanish cultural icon and was chosen as one of the 12 Treasures of Spain.
The theatre has undergone several renovations, notably at the end of the 1st century or early 2nd century CE (possibly during the reign of Emperor Trajan), when the current facade of the scaenae frons was erected, and another in the time of Constantine I (between 330 and 340), which introduced new decorative-architectural elements and a walkway around the monument. Following the theatre"s abandonment in Late Antiquity, it was slowly covered with earth, with only the upper tiers of seats (summa cavea) remaining visible.