Perched high on a volcanic outcrop above green fields and vineyards, Orvieto is a postcard-perfect Umbrian hilltop town.
Comely Corsham sits on the edge of the Cotswolds, just outside Bath and surrounded by the pretty Wiltshire countryside.
With its age-old fortresses, watchtowers, Moorish streets and Roman remains, this attractive Spanish port has history around every corner.
Arras is a gem of a small city in northern France with large Baroque-style squares, an ornate town hall, belfry and a majestic star-shaped citadel.
An astonishing 10,000 miles (16,093km) of tunnels were dug here in total, and locals often discover new openings to mine shafts in their gardens each spring when the snow melts.
With its gorgeous Grote Markt square, grand city hall, gabled guild houses and art-filled Flemish museums, Antwerp is a fantastic city to explore.
Underground passages were key to its construction when the Knights Hospitaller of Malta set about building the fortress after the Great Siege of 1565.
Another centuries-old fortified city sitting above an intriguing network of tunnels is the Estonian capital, Tallinn.
A quintessential fortified Tuscan city, Siena is packed with medieval treasures and steeped in age-old traditions.
There is evidence the caves have been occupied since the Palaeolithic period, but by the 1950s the dwellings were overcrowded and home to impoverished families and their animals with no running water or electricity.