This 'reconstruction' by Piranesi from the 1760s shows the four Caryatids found on the Via Appia in Rome - the figure to the left has only an original head on a different body, and the figure to the right is a Roman copy of the Erechtheion Caryatids now in the Villa Albani.
Two of the Caryatids, now in the Villa Albani, were discovered in the 1600s, and two more in the same vineyard in 1764. The area, between the second and third milestones of the Via Appia, has yielded a number of inscriptions allowing us to securely identify it as the Triopion built by Herodes Atticus.
Seen above in 1748 in the engraving by Piranesi, and in a reconstruction to the left sketched by Thomas Hope (paper watermarked 1812).
These four central figures are the 2nd century AD Roman statues which Herodes Atticus had carved to honour Regilla. The general sentiment is that since she was a priestess of Demeter, and depicted thus at Olympia, the Via Appia monument must have some link to the cult of Demeter.
The statues now in the Villa Albani are only available in poor quality black and white photographs, so I thought it would be more interesting to show these 18th century drawings of them. The figures are numbered according to the Piranesi reconstruction, which had nothing to do with their ancient positions.
Mithras slaying a bull from the Baths of Mithras and a cippus from a Mithraeum were found in Ostia, both bearing the signature of Kriton of Athens, and of a similar date to the carved columns. A copy of the Kriton Mithras was in the Giustiniani collection (see here for more on the Mithras; b/w photo here).
The name is unusual, so he may be related to the M. Umbilius Maximinus son of Marcus that was a patron of Ostia, and recorded in a AD 200 funerary inscription at the Serapeion, and who is recorded into the 3rd century (see p. 335 here and here)
If this is the same sculptor, close examination of the women has led me to believe that they were almost entirely recut and reworked, rather than just restored, in modern times, probably in the studio of Cavaceppi. A small scale replica in Germany by him lends credence to this theory, as do recently found drawings of the figures by an artist from within his circle (Private Collection, London; formerly owned by Kenneth Clark). The sketch book included studies of the Monte Porzio figures, at least one of which was in his studio at the time of his death.
The sixth figure in the Piranesi reconstruction is a Roman copy of the Erechtheion Caryatids, which is now also at the Villa Albani, where it was kept outdoors because it was dismissed as a modern copy, and is now in very poor condition.
Figures 2 and 3 were found in 1764: 2 is now in the Braccio Nuovo of the Vatican, and 3 was bought by Charles Townley and is now in the British Museum.
Townley's collection is well documented.
This view shows Charles Townley in his Sculpture Gallery by Johann Zoffany, 1782 (source)
He re-arranged his sculptures when he increased his collection as seen in this view of the Dining Room at Park Street, Westminster, by William Chambers, London, 1794-95 (source). The Caryatid is visible after the Venus in the middle of the right wall.
This figure in Athens is replicated by Piranesi figure 4 in the Villa Albani.
What's interesting is that the Athens figures were excavated close to the Little Metropolis, which has this unusal Doric metope frieze built into it. I know of only two similar friezes, both from the late Hellenistic period: one on Samos, and one from the Propylon at Eleusis. Because the Eleusis gateway had Caryatids, and Caryatids (of the Tralles-Cherchel type) decorated the Hadrianic gate of the City Eleusionion in the Agora ... the general assumption is that this frieze was brought over from the City Eleusinion in the Byzantine period. I would argue instead that the frieze came from the same structure as the Caryatids above. It's iconography is that of Eleusis, but the iconography and cult of Demeter were imitated by the cults of Isis in Athens - and Pausanias mentions a sanctuary of Serapis in the area. My guess is that these copied a variety of early Hellenistic figures, perhaps created for the Seleucids or Ptolemies (who favoured similar melon-hairstyles), and decorated a shrine of Isis within a Hellenistic Serapeum built by a later Ptolemy in Athens.