Wikipedia
Nisaea was the main port of ancient Megara.
According to Thucydides (4.66), the distance of the port from Megara itself was about eight Greek furlongs; Fraser says it is a mile and a half from the modern town. When Megara joined the Athenian alliance c. 459 BC, the Athenians built and garrisoned two long walls between Megara and Nisaea; in 424 the Megarians got possession of the walls and destroyed them, but in the fourth century they were rebuilt by Phocion and were still extant in Strabo's time.
The hill of St. George on the eastern side of the harbor "appears to have been the acropolis of Nisaea mentioned by Pausanias."
Nisaea is a genus in the phylum Proteobacteria ( Bacteria), which contains two species, namely N. denitrificans and N. nitritireducens, which were described in 2008.