Carnival has already come and, undoubtedly, one of the famous Carnival in the world is Venice's Carnival.
In Second Life there is an amazing destination themed in Venice city. You can be into a very realistic reconstruction of the Italian city of canals at Dance Park Prada Sim, in the virtual world.
Of course, you can visit St. Mark's Square, the Cathedral, the Bridge of Sighs, the Rialto Bridge, its palaces, sail on gondola, etc.
Always is a good time to visit this wonderful city, but in Carnival would be essential.
Here is the taxi to Venice in Second Life