The Brinkkala Mansion dominates the square's southern edge, its wooden balcony added during renovations from 1884 to 1886 specifically to continue a tradition older than the building itself. Before the Great Fire of 1827 destroyed the original town hall, Christmas Peace was proclaimed from its "doors and windows" according to the ancient saying. When the mansion rose from the ashes, it inherited the duty. The earliest records of the Brinkkala Mansion date to the 16th century, when it served as a townhouse for the owners of Brinkhall Manor in nearby Kakskerta. Today it houses art galleries and banquet halls, but its claim to fame remains that December balcony moment when all of Finland pauses.

The Great Fire of 1827 carved the Old Great Square in half. Before that catastrophic night, buildings lined all sides of the medieval marketplace. After the flames died, the entire northern block was converted into Porthaninpuisto park - an open space that would never burn. Only the southern row of structures survives, each one rebuilt after the disaster in the neoclassical style that architect Carl Ludvig Engel imposed on the reconstructed city. The Old Town Hall stands on its medieval foundation but wears an 1899 factory's three-story shell, acquired by the city in 1932. These buildings remember their past through their walls but disguise it with new facades.

Captain Hjelt wasted no time after the fire. In 1830, he purchased a burned site along the square and constructed what would become Finland's only surviving building in the Russian Empire style from Saint Petersburg. The Hjelt Mansion, an imposing two-story stone structure, served the police department through the 1930s, then hosted the children's section of Turku City Library and the Cultural Centre. In 2008, the building found a new identity as the "Itameritalo" - the Baltic Sea House - home to four international organizations focused on the Baltic region. The architecture of a Russian imperial summer palace now houses European environmental cooperation.

The Turku Medieval Market transforms the Old Great Square each June and July into a living museum of the past. Craftsmen demonstrate traditional trades, vendors sell period goods, and performers in historical costume fill the cobblestones and courtyards. The market spills from the square into Porthaninpuisto park and down Luostarin Valikatu - the narrow lane that once connected the Kaskenmaki Monastery to Turku Cathedral during the Middle Ages. This annual gathering draws visitors into the square's original purpose: commerce, community, and the vital pulse of a medieval trading city.

Katedralskolan i Abo, a Swedish-language senior high school, stands on foundations predating the fire. The site once held the Hovratt, the regional court of appeals, before Engel designed the current Empire-style building. But the location's educational heritage runs deeper still. Records suggest a school operated under the authority of Turku Cathedral here in the late 13th century - the Turun katedraalikoulu - making this corner of the Old Great Square one of Finland's oldest sites of continuous learning. Students walk halls where their predecessors studied seven centuries before them.