What "intact medieval" means
Most European old towns are 17th–19th century reconstructions or pastiche. Truly medieval (12th–15th century buildings, original street pattern, surviving walls and gates) is rare. The cities below are the legitimate UNESCO-listed survivors.
Tallinn
Tallinn Old Town — the most intact Hanseatic medieval old town in northern Europe. Town Hall (1404), Toompea Castle, complete wall with 20+ towers. UNESCO. Compact (1.5 km wide). November–March cold but mostly tourist-empty.
Bruges
Bruges Belfry, Markt, Burg square, canals all medieval intact. Tourism heavy but old town genuinely 13th–15th century. UNESCO. Day-trip from Brussels or stay overnight after 5pm crowd disperses.
Carcassonne
Walled medieval city in southern France. Cité de Carcassonne is double-walled — Roman + medieval. Heavily restored by Viollet-le-Duc (controversial), but the structure authentic. UNESCO. Day-trip or overnight from Toulouse.
Toledo
Toledo "City of Three Cultures" — Christian, Jewish, Muslim medieval coexistence visible in architecture. Synagogues, mosques (now churches), cathedral, Alcázar. UNESCO. 30-minute AVE high-speed from Madrid.
Český Krumlov
Czechia's Krumlov — castle, river bend old town, intact medieval streets. UNESCO. Crowded summer day-trippers from Prague (3h drive); overnight reveals quieter early mornings.
Rothenburg ob der Tauber
Bavaria's medieval icon. Tower walls intact and walkable; old town reads as 14th-century film set. Romantic Road tourism heavy June–September; April or November better.
San Gimignano
Tuscany's "medieval Manhattan" — 14 surviving stone towers (originally 72). UNESCO. Day-trip or overnight from Siena or Florence.
Strategy
Stay overnight in the old town, not surrounding modern city. Day-trippers flood 11am–4pm; early morning and evening have the towns to yourself. Skip July–August in popular ones (Bruges, Rothenburg).