Dubrovnik has everything you would want for a medieval setting, City walls with gates and fortifications, narrow streets and a port. Its little wonder that it has hosted a number of movies and TV series. When I was there you couldn't miss the Game of Thrones merchandising and everywhere you turned reminded me of scenes from the series.
Read more on the (Wiki link) or click (here) for a map of Dubrovnik.

Franjo Tudman Bridge

Ploce gate (Plo-chay)

St. Blaise

St. Dominik

Chastity stairs leading to St Dominik

Swallows invading the Stradun (the main street)

Sponza Palace

Square of the Loggia

Birds over Orlando's Column

Streets climb like a scene from Inception

Rectors Palace

Inside Rectors Palace

Hand rail

Game of Thrones merchandising was everywhere.

Gunduliceva Poljana

Big Onofrio's fountain (1438)

Monastry and pharmacy

Pile gate (Pea-lay)

Shelling of old town during the 1991 war

Despite the thickness of the city walls they fail to keep out giant marauding Pigeons and Swallows. (Image of pigeon may not be to scale)

Lovrjenac fortress

Lovrjenac fortress they were filming for Hamlet

On Lokrum island

Heading to the fort (Got season 2)

Game of Thrones throne

Bolognase Pizza at Mea Culpa

Minceta Tower
The below images are all borrowed from the Interweb