Passing under the round City Tower, the former main medieval town entrance that gave access to the coast, you enter the centre of Rijeka’s Old Town.
Located in the modern-day Ivan Kobler Square, there was once a more compact municipal centre called Placa, which served the significantly smaller fortified medieval town. The most knowledgeable historical interpretations of Rijeka Town present it as vertically elongated, framed to the north and south by the City Tower and the Town Hall, and to the east and west by chains of houses.
The northern part of Rijeka was dominated by the lord's castle, the eastern part featured the main commoners’ church with a cemetery, to the west there was a spacious cloistered enclosure, and here, in the south quarter, near the embankment and the beach market under the town walls, there was the vibrant heart of the Town. There, the citizens of Rijeka would meet to listen to the proclamations of the Town Crier, seal contracts and buy and sell on the open market or in stores situated in the ground floors of houses. Only traces of those houses remain now, with several old walls integrated into more modern buildings, a baroque lintel with the former owner’s coat of arms and an arched underground corn house. In the near past was the former town “Greenmarket” where fruit and vegetables were sold.
http://www.visitrijeka.eu/What_To_See/Architecture/Ivan_Kobler_Square