Venice

Venice was a city in Italy on the Adriatic coast. (BFA: The Stones of Venice)  Originally a collection of huts built on marshland by people running from Atilla the Hun, it grew into, according to the Doctor, "one of the most powerful cities in the world". Influenced by a variety of cultures, it was the hub of a trading empire, famously connected by an intricate series of canals. By 1580 it already had a population of some 200,000 people. (DW: The Vampires of Venice). Because of its improbable architecture at or below sea level, it was gradually sinking over time. The Doctor's original incarnation once told Steven and Vicki that it had disappeared into the ocean "centuries before either of [them] were born". (MA: The Empire of Glass) However, it was the Doctor's eighth incarnation that was the first version of the Doctor to actually witness the demise of Venice. In the 23rd century, it finally succumbed the weight of its illogical design, and disappeared into the lagoon from whence it had originally come. (BFA: The Stones of Venice)

At least three personas of the Doctor found it an incredibly attractive city to visit. The Doctor's original incarnation once told Steven and Vicki that the marshes immediately surrounding the city was a "wonderful place", primarily based on the quality of the air and shoreline. (MA: The Empire of Glass)  The Doctor's eighth self told Charlotte Pollard it was "magnificent and charming and often quite silent and sinister", and a city with a desolate look in the morning that was reborn by its own lights every night. (BFA: The Stones of Venice)  In his eleventh life, the Doctor took Rory Williams and Amy Pond to the city as a wedding present. He described it as an "impossible" and "preposterous" city "constantly being invaded, constantly flooding, constantly . . . just, beautiful". He was confident Amy and Rory would love it because many famous humans before them — including Byron, Napoléon Bonaparte, and Casanova — did. (DW: The Vampires of Venice)  On two occasions, Venice has been visited by aliens which had tecnology to allow them to appear human to the Venicians, the Saturnynians (Perception filter) and the Jamarians (Hologuise Generators).