Large framed mid 19th Century micro mosaic plaque of the Pantheon Rome

A fine micromosaic showing the view across the Piazza della Rotonda from the North with the fountain and obelisk to one side and the Pantheon in the middle ground with apartments and other buildings surrounding the square. Set in a rectangular basalt plaque and framed in its original heavy ebonised frame with projecting corners and pyramid bosses and secured into the frame with steel supports and a large steel hanging ring - unsigned but marked to the back with stencilled catalogue numbers - overall dimensions framed 350 x 315mm - depth of frame 53mm - visible image of the plaque 171 x 130mm - oval area of micromosaic  140 x 110mm - c.1850 Italy