It’s a construction site, but the whole city sets rather low in elevation.
FRom another article. The site is formerly a fruit and vegetable market which is under construction for a tunnel across the Marmora—but way before that it was a harbor and they have found 34 ships under the mud.
“In fact, Yenipaki was also once the site of the Harbour of Theodosius. Commissioned by Emperor Theodosius I (379-395 AD), it was built to meet the needs of the Eastern Roman Empire’s rapidly growing new capital, and was one of the most important harbours of the Byzantine period. Though the location of the harbour was already known – both from written sources and ancient maps – no-one knew its layout, size or exact position. As the new project demonstrates, the Harbour of Theodosius no longer lies on the shore but about 1.5km inland. This is because, over time, the area was silted up with alluvium carried by the Lycos (Bayrampas, a) River, and was then further reclaimed by farming activity and construction in the city.”