Hellenistic art. The Laocoön and His Sons in the Vatican Museums, one of only a very few sculptures which are today regarded as especially fine examples of the art of antiquity, and which was already in antiquity declared to be a "masterpiece surpassing all other works of painting and sculpture", may be based on an original that also came from a Pergamene workshop and was created at about the same time as the altar. It is noteworthy that the opponent of the goddess Athena on the side of the Giants, Alcyoneus, strongly resembles Laokoon in posture and portrayal. When the frieze fragment was found, a cry was to be heard, "Now we have a Laokoon too!" From discovery to presentation in Berlin From antiquity to 19th century excavations With the rise of Christianity, the altar lost its function at the latest in Late Antiquity,. In the 7th century the acropolis of Pergamon was strongly fortified as a defense against the Arabs. In the process the Pergamon Altar, among other structures, was partially destroyed in order to reuse the building material. The city was nevertheless defeated in 716 by the Arabs, who temporarily occupied it before abandoning it as unimportant. It was only resettled in the 12th century. In the 13th century Pergamon fell to the Turks. Between 1431 and 1444 the Italian humanist Cyriacus of Ancona visited Pergamon and described it in his commentarii (diary). In 1625 William Petty, chaplain to Thomas Howard, 21st Earl of Arundel, a collector and art patron, traveled through Turkey, visited Pergamon, and brought back to England two relief panels from the altar. These pieces were forgotten after the Earl's collection was dispersed and were only rediscovered in the 1960s. For this reason these two panels are lacking in the Berlin reconstruction. Other travelers known to have visited Pergamon during the late 18th and early 19th centuries were, for example, the French diplomat and classical scholar Comte de Choiseul-Gouffier, the English architect Charles Robert Cockerell and two Germans, the archaeologist Otto Magnus von Stackelberg and the classical scholar Otto Friedrich von Richter. Choiseul-Gouffier was the first to propose excavations in Pergamon; the other three travelers made drawings of the city's acropolis. The German engineer Carl Humann came to Pergamon for the first time in 1864/65. He was charged with geographic investigations and repeatedly visited the city in the following years. He urged the preservation of