Pius VII decided in 1806 to build the Braccio Nuovo, but it was not until 1817 (after the sculptures that Napoleon had "deported" to Paris were returned) that the scheme could be carried out.  The new wing was planned by the Roman architect Raffaele Stern; He died on December 30 1820, and Pasquale Belli took over the job of supervising the construction.  The new wing was inaugurated in 1822.  The reliefs above the niches are by Massimiliano Laboureur.  The ancient mosaics (2nd century A.D.) in the floor are from excavations near Tor Marancia, on the Via Ardeatina (the representation of the adventures of Ulysses is especially noteworthy).

     The statues below and the man with a mask on the left are unknown works. (at least, they are unknown to us) 

The new wing of the Vatican Museums is home to Colossus of the Nile (lower left).   the river god, identified by the sphinxes and crocodiles, is represented as a dispenser of blessings.  The 16 boys are thought to be an allusion to the number of cubits the level of the Nile rises when it floods, fertilizing the region which it crosses.  The reliefs on the base represent life on the banks of the river.  It is a 1st century A.D. Roman work most likely based on a Hellenistic original.

Credit for the Information in this tour:

Papafava, Francesco. Ed. Guide to the Vatican Museums and City. Vatican City: Tipografia Vaticana., 1986

Also, I have included information from the exhibits at the Vatican Museum and notes from the lecture of Professor B. Nucci (University of Maryland University College - European Division)