Mount Olympus (Greek: Όλυμπος Olympos) is the highest mountain in Greece. It is located in the Olympus Range on the border between Thessaly and Macedonia, between the regional units of Pieria and Larissa, about 80 km (50 mi) southwest from Thessaloniki. Mount Olympus has 52 peaks, deep gorges. The highest peak, Mytikas (Μύτικας Mýtikas), meaning "nose", rises to 2,919 metres (9,577 ft). It is one of the highest peaks in Europe in terms of topographic prominence.

Olympus is notable in Greek mythology as the home of the Greek gods, on Mytikas peak. It is also noted for its exceptional biodiversity and rich flora. It has been a National Park, the first in Greece, since 1938. It is also a World Biosphere Reserve.

Every year, thousands of visitors admire its fauna and flora, tour its slopes, and climb its peaks. Organized mountain refuges and various mountaineering and climbing routes are available. The usual starting point for climbing Olympus is the town of Litochoro, on the eastern foothills of the mountain, 100 km (62 mi) from Thessaloniki.

The whole region of Pieria's Olympus was declared archaeological and historical site for the preservation of its monumental and historical character. Five km away from the sea is Dion, sacred city of the ancient Macedons, dedicated to Zeus and the Twelve Olympians. Its prosperity lasted from the 5th century BC to the 5th century AD. The excavations, continuing since 1928, have revealed numerous findings of the Macedonian, the Hellenistic and the Roman period. Currently there is a unique archaeological park of 200 hectares, with the ancient town and the sacred places of worship, outside its walls. Many statues and other invaluable items are kept in the nearby Dion's archaeological museum. Pimblia and Leivithra, two other towns in Olympus' region, are related to Orpheus and the "Orphic" mysteries. According to a tradition Orpheus, son of Apollo and Calliope (one of the Muses), taught here the mystic ceremonies of worship of Dionysus (also known as Bacchus). By the sea, in a strategic position, at Macedonia's gates is located Platamon Castle, built between 7th and 10th century AD in the ancient town of Heracleia. To the north the ancient Pydna is located. Here, in 168 BC, the decisive battle between the Macedonians and the Romans took place. Between Pydna and Mount Olympus are a fortified bishops seat from the Byzantine period called Louloudies and the Macedonian Tombs of Katerini and Korinos.

In the Olympus region, there are also several Christian monuments, among them the highest-altitude chapel of Orthodox Christianity, dedicated to Prophet Elias, in Greek tradition associated with mountaintops, on the summit of the same name (Προφήτης Ηλίας Profitis Ilias), at 2,803 m. It was built in the 16th century by Saint Dionysios of Olympus, who also founded the most significant monastery in the region. The Old Monastery of Dionysios (altitude 820 m) lies in Enipeas' gorge and is accessible by car from Litochoro. It was looted and burned by the Ottomans and in 1943 it was destroyed by the German invaders, who suspected it was a guerilla den. Nowadays it has been partially restored and operates as a dependency of the New Monastery of Dionysios, that is outside Litochoro. On Olympus' southern foot, in a dominant position (820 m) in Ziliana gorge, there is the Kanalon Monastery, 8 km away from Karya. It was founded in 1055 by the monks Damianos and Joakim and since 2001 it has been restored and operates as a convent. Further west, in the edge of Mavratza stream, at 1,020 m, there is the Agia Triada Sparmou Monastery, that flourished in the early 18th century, possessed great property and assisted to establish the famous Tsaritsani' school. It was abandoned in 1932, but in 2000 it was completely renovated and reopened as a male monastery, affiliated to Elassona's diocese.

The third highest peak of Mt Olympus, called Agios Antonios (Άγιος Αντώνιος "Saint Anthony", 2,817 m), is known to have been the site of a sanctuary of Zeus in antiquity based on archaeological finds discovered in 1961. In the modern era, a series of explorers tried to study the mountain and to tried to reach its summit. Examples include the French archaeologist Leon Heuzey (1855), the German explorer Heinrich Barth (1862), and the German engineer Edward Richter. Richter tried to reach the summit in 1911 but was abducted by klephts, who also killed the Ottoman gendarmes that accompanied him.

It was just one year after the liberation of northern Greece from Ottoman rule, on 2 August 1913, that the summit of Olympus was finally reached. The Swiss Frédéric Boissonnas and Daniel Baud-Bovy, aided by a hunter of wild goats from Litochoro, Christos Kakkalos, were the first to reach Greece's highest peak. Kakkalos, who had much experience climbing Olympus, was the first of the three to climb Mytikas. Afterwards, and till his death in 1976, he was the official guide on Olympus. In 1921, he and Marcel Kurz reached the second highest summit of Olympus, Stefani. Based on these explorations, Kurz in 1923 edited Le Mont Olympe, a book that includes the first detailed map of the summits. In 1928, the painter Vasilis Ithakisios climbed Olympus together with Kakalos, reaching a cave that he named Shelter of the Muses, and he spent many summers painting views of the mountain. Olympus was later photographed and mapped in detail by others, and a series of successful climbs and winter ascents of the steepest summits in difficult weather conditions took place.

Climbing Mount Olympus is a non-technical hike, except for the final section from the Skala summit to the Mytikas peak, which is a YDS class 3 rock scramble. It is estimated that 10,000 people climb Mount Olympus each year, most of them reaching only the Skolio summit. Most climbs of Mount Olympus start from the town of Litochoro, which took the name City of Gods because of its location at the foot of the mountain. From there a road goes to Prionia, where the hike begins at the bottom of the mountain.

Generally speaking Olympus' climate can be described as one of Mediterranean type with continental influence. Its local variations is the result of the impact of the sea and the rugged relief of the region. In the lower locations (Litochoro and the foothills) the climate is typically Mediterranean, i.e. hot and dry in the summer, while humid and cold in the winter. Higher it is more humid and severe, with more intense phenomena; in these locations it often snows all over the winter, while raining and snowing is not unusual, even in the summer. The temperature varies in the winter from −10 °C to 10 °C and in the summer from 0 °C to 20 °C, while winds are an almost everyday occurrence. Generally the temperature falls 1 °C per 200 m of altitude. As the altitude rises, the phenomena are more intense and the variations of temperature and humidity are often sudden.