The ChR Keras was a massive new bird-of-prey launched around the turn of the 2270s decade. It was commissioned at the order of Gaius, Praetor of the Romulan Star Empire, in honor of his father, Romulan commander Keras.
The Keras was easily bigger than six of the older Vas Hatham-class and its bridge spanned two levels. It was equipped with a cloaking device and warp drive, and a cavernous shuttle bay at its stern.
In 2267, Praetor Gaius personally took command of the Keras when the USS Yorktown under Commodore Number One entered the Romulan Neutral Zone. (TOS comic: "Schism, Issue 2")