GONNUS or GONNI(Γόννος, Herod., Strab.; Γόννοι, Polyb., Steph. B.: Eth. Γόννιος, also Γούνιος, Γονατᾶς, Steph. B. s. v.), an ancient town of the Perrhaebi in Thessaly, which derived its name, according to the later Greek critics, from Gonneus, mentioned in the Iliad. ( Il. 2.748; Steph. B. s. v. Γοννοί.) Its position made it one of the most important places in the north of Thessaly. It stood on the northern side of the Peneius, near the entrance of the only two passes by which an enemy can penetrate into Thessaly from the north. The celebrated vale of Tempe begins to narrow at Gonni; and the pass across Mt. Olympus a little to the west of Tempe leads into Thessaly at Gonni. It was by the latter route that the army of Xerxes entered Thessaly. (Hdt. 7.128, 173.) The position of Gonni with respect to Tempe is clearly shown by the numerous passages in which it is mentioned by Livy. After the battle of Cynoscephalae, in B.C. 197, Philip fled in haste to Tempe, but halted a day at Gonni, to receive such of his troops as might have survived the battle. (Liv. 33.10; Plb. 18.10.) In the war against Antiochus, in B.C. 191, when the king, having marched from Demetrias, had advanced as far north as Larissa, a portion of the Roman army under the command of App. Claudius marched through the pass across Mt. Olympus, and thus arrived at Gonni. On this occasion Livy says that Gonni was 20 miles from Larissa, and describes it as situated in ipsis faucibus saltus quae Tempe appellantur.(Liv. 36.10.) In B.C. 171 it was strongly fortified by Perseus; and when this monarch retired into Macedonia, the Roman consul Licinius advanced against the town, but found it impregnable. (Liv. 42.54, 67.) Gonni does not occur in history after the wars of the Romans in Greece,. but it is mentioned by Strabo (9. p. 440; Ptol. 3.13.42).
The site of Gonni is fixed by Leake at a place called Lykóstomo, or the Wolf's Mouth,in the vale of Derelí, at the foot of a point of Mt. Olympus, about a mile from the Peneius. Here are some remains of a Hellenic city, mixed with other ruins of a later date. It would therefore appear that the town of LYCOSTOMIUM(Λκοστόμιον), which occurs in Byzantine history as early as the eleventh century (Cantacuz. 2.28, 4.19), was built upon the site of Gonni. (Leake, Northern Greece, vol. 4. p. 388.)