THESSALONIKI, GREECE—The 2,300-year-old “Middle Road” unearthed during subway construction in the heart of modern Thessaloniki will be preserved in situ. The construction company had wanted to move the avenue and its buildings, but archaeologists collected more than 12,000 signatures and produced an alternate plan that will preserve up to 84 percent of the site in place. The marble street, which led to the harbor and featured a monumental Roman gate, was used for 700 years. “This was a central crossroads where the city’s central market and public buildings were located,” said Despoina Koutsoumba, head of the association of Greek archaeologists. More than 50,000 coins, and thousands of vessels, lamps, vials, and jewels have been uncovered.