Ancient Greeks made offerings to sanctuaries for a variety of reasons, such as to seek favor with the gods, give thanks for blessings received, or ask for assistance in a time of need. The types of offerings varied, but they generally fell into these categories:

• Animal Sacrifices: This was the most common type of offering made at ancient Greek sanctuaries. Animals such as sheep, goats, cows, and pigs were sacrificed, and their meat was usually shared among the community in a feast after the sacrifice. The type of animal sacrificed often depended on the god or goddess being honored. For example, a cow might be sacrificed to Hera, the goddess of women and marriage, while a goat might be offered to Dionysus, the god of wine and revelry.
• Libations: Libations were liquid offerings, typically of wine, olive oil, milk, or honey, poured out onto a sacred altar or directly onto the ground. Wine was a particularly common libation, often poured out in honor of Dionysus.
• Food Offerings: These could include cakes, fruits, and grains. Such offerings were often made in connection with agricultural festivals, as thanks for a good harvest or to ensure future bounty.
• Votive Offerings: These were gifts given to the gods that were often left in a temple or sanctuary. They could be quite varied and included statues, jewelry, weapons, and other valuable goods. Some of these were quite elaborate and could be works of art in their own right.
• Ritual Objects: Objects used in religious rituals, such as incense burners, lamps, and tripods, could also be left as offerings.
• Tithes: In some cases, Greeks would promise a percentage of their income or spoils of war to a god, if the god would help them in some way. If their request was granted, they would then pay this tithe to the god's sanctuary.
Now, as for the specific locations you mentioned: Mount Olympus: This was believed to be the home of the Twelve Olympian gods in Greek mythology. As such, it would have likely seen a wide range of offerings, reflecting the diverse domains of these gods. Temple of Dion: Dionysus was the god of wine, revelry, and theatre. Offerings to him might include libations of wine, animal sacrifices (particularly of goats), and perhaps theatrical performances. Pella: This was the capital of the Kingdom of Macedon and the birthplace of Alexander the Great. It might have seen offerings reflective of its status as a royal city, perhaps including valuable votive offerings. Vergina and Aigai: These locations are associated with the ancient Macedonian royal family. Vergina is the site of the royal tombs, and Aigai was the ancient capital. Offerings here might have been made to honor the dead and ask for their favor in the afterlife. Thessaloniki: This city has a long history, dating back to ancient times. It would have seen a wide range of offerings over the years, reflecting the diverse gods worshipped there.