During Heinrich Schliemann's excavations at Hisarlik, he discovered 270 artefacts buried where Priam's palace supposedly stood. He called these artefacts 'Priam's Treasure'. If Priam's belongings are at Hisarlik then this is evidence for Troy being at this location.
Schliemann thought that Priam must have hidden his valuable treasure somewhere in the city. The King wouldn't have wanted Trojan treasures to fall into Greek hands if the city was captured. Finding this hidden treasure was of great importance to Schliemann, not only for its value but also as evidence that Hisarlik was, indeed, the site of Troy. On 31st May 1873, at Troy II, Schliemann found what he was looking for. The artefacts were all closely packed together, probably having been initially buried in a chest. These 270 items included gold jewellery, headdresses, silver ingots, bronze weapons, a copper cauldron and many other treasures. Schliemann actually published a photo of his wife Sophia wearing the gold jewellery and diadem found in this treasure cache, to show off his findings to the public. The treasure was certainly extensive enough and valuable enough to have belonged to royalty. Schliemann got into trouble with the Ottoman authorities by smuggling the treasure out of Ottoman territory. Some say that his wife, Sophia, hid some of the treasure in her underwear. Eventually, Schliemann was sued by the Ottoman authorities, but the artefacts were later displayed in various museums.
Priam's Treasure was found in the layer Troy II, but Priam would have been alive during the time of Troy VI or VIIa, which was occupied hundreds of years later. Frank Calvert, the man who first thought Troy was at Hisarlik, told Schliemann that the treasure was too old to have belonged to Priam, but Schliemann refused to listen to any critics. Schliemann showed a complete lack of respect for the treasure by smuggling it out of Ottoman territories illegally, and it is likely that he cared more about achieving fame and wealth than uncovering history. He had much to gain from lying about the origin and value of the treasure.
[P1] Schliemann found treasure buried at the ruins of Priam's palace in Hisarlik. [P2] The treasures were discovered to be a cache of gold, silver, and other artefacts fit for royalty. [P3] The treasures belonging to King Priam of Troy show that Troy must have been at Hisarlik.