From the beginning, Szczecin got good press: it is first mentioned by Ptolemy in the 1st century AD, and continued to garner attention over the ages due to its strategic location along the Oder. It used that location well, growing into a maritime and industrial center rivalling nearby Gdansk and Frankfurt am Oder.
But with strength comes attention. Szczecin got it initially from the newly-baptized Polish king Mieszko I who incorporated the city and the surrounding regions into his newly-made kingdom near the end of the 10th century. Following that Polish act, the Danes came to town in the 12th century and controlled Szczecin for about 40 years. Once free of the Danes, Szczecin developed, added Germans and Flemings to its local Polish population, and eventually joined the Hanseatic League.
The German population swelled with the Reformation, and Szczecin's ties with a Catholic Poland loosened. They loosened even more when the Swedes invaded in 1630 and overstayed for 100 years, and then completely when the town was sold to Prussia in 1720. Around that time, the woman later to become Catherine II was born, spent 15 years of her life here, and then moved on to Russia.
And the saga continues. After some back-and-forthing over the next century, with the French briefly taking over in the early 1800's, the Prussians added more to Szczecin's development than many of its former occupiers. Around the 1870's the city walls came down, and coincidentally, the Polish population went up. But not enough to matter after WWI, when Szczecin suffered terribly from the land-compromise which isolated it from its natural market. Such a problem disappeared after WWII when Sczcecin at long last returned to Polish hands. Since, it has rebuilt, and redeveloped into a strong maritime center.