You shouldn't translate 'Peninsula', because it's part of a proper name, like 'Buckingham Palace' or 'Piccadilly Circus'. If words are capitalised, they are names and should generally not be translated. I'd suggest transcribing the full name 'Pensinsula Barracks' as it is, and preceding it or following it with the Russian word for 'barracks' to explain to your readers what this place is.

'Peninsula' is a common noun that means a piece of land that is almost an island, being almost completely surrounded by water. I think it's полуостров in Russian. There are various well known peninsulas, such as the Iberian Peninsula (comprising Spain and Portugal), the Florida Peninsula and the Kamchatka Peninsula. Gibraltar is another famous one. I don't know why this name was given to these barracks. It was probably in reference to a peninsula that had particular significance in the history of the regiment to which the barracks belonged. Maybe you could use an adjective form of полуостров in your translation?

Thank you for your answering.

 I've learned that the majority of the British military barracks were called in honor of battles, military numbers or the district. Also I know, that this name the Peninsula Barracks recieved after 1904 (more later). I would like to learn with what events it was connected.

Our russian tourists always are interested why this place have such name. Sometimes guides think up the amazing history and tell tourists.

By the way, I have information why London and the Winchester were so called. (they came from ancient English words)

By the way, this town, Winchester, organizes a Christmas action for future travelers on Facebook. If you are interested to visit this town next year you can take part here: http://www.visitwinchester.co.uk/

Unfortunately I can't visit this town next year although I am eager.