Every Medici appointee needed a Roman palazzo, and Cardinal Altemps bought one from a declining family. Rome, in those days of sequential family papacies, was like Washington DC is at the change of presidential administrations -- lots of families from the old administration moving out and new appointees arriving and looking for housing. Each new owner would expand and aggrandize the property, so the important palazzi were always "under construction." The palace had been begun before 1477 by Girolamo Riario, was continued by Cardinal Francesco Soderini of Volterra from 1511 to 1523 and was completed after 1568 by Cardinal Altemps and his descendents, for whom Martino Longhi the Elder worked. Longhi was responsible for the turreted "belvedere", a much copied architectural innovation. The last Altemps heir to inhabit the building appears to have been one Lucrezia who married a French Government official in the mid-1800's. They sold the place to the Papacy who used it for a seminary for foreigners, mostly German and Spanish, but the building was virtually abandoned by 1982 when the Italian Government bought the property and began a careful and thorough restoration lasting 15 years.
Cardinal Altemps started collecting antique sculptures as soon as he moved in, and 16 of his statues are once again displayed in the museum. The bulk of his collection was dispersed when the Medici lost power and the Roman branch of the Altemps began its long downward slide. The finest pieces went to the Vatican museums and others to the British Museum and the Louvre.
Some of the sixteen Altemps statues are part of the Ludovisi Collection, which forms the bulk of what is displayed in Palazzo Altemps. Cardinal Ludovico Ludovisi, a nephew of Pope Gregory XV (reigned 1621-23) acquired part of the Altemps collection to decorate the splendid villa and gardens he built for the use of the Pope and his family near Porta Pinciana on the site where Julius Caesar and his heir, Octavian (Caesar Augustus), had their villa. (The core of the Ludovisi site is now the American Embassy and the Banca Nazionale del Lavoro on Via Veneto). The Ludovisi family, starting with Cardinal Ludovico, also acquired pieces from the Cesi and Mattei family collections and added to them ancient Roman sculptures excavated from the grounds of their Villa and elsewhere in Italy. Ludovico brought in Gianlorenzo Bernini and Alessandro Algardi to restore (and "complete") the statuary. Some pieces were sold out of the Ludovisi collection as early as 1665 but the remaining collection and the buildings of the villa that housed it (acquired by Gregorio Boncampagni) became a major attraction for "tourists" -- rich folks on the "Grand Tour" of Europe -- just as the Villa Borghese is for tourists today. Sale of casts and copies of the more famous pieces, in fact, provided part of the income that kept the Boncampagni family afloat.
The Ludovisi/Boncampagni holdings of land, buildings, and art are very well documented, and most of the sculpture was catalogued by Johann Winckelmann, the 18th century's "foremost authority" on classical works in Rome. The collection expanded again in the 19th century, but, after the reunification of Italy, the fortunes of all of Rome's noble families began to decline. In 1883, the Boncampagni sold off most of their land holdings inside Porta Pinciana, and construction of the Via Veneto and the surrounding neighborhoods began. Palazzo Piombino, later renamed the Palazzo Margherita (the front part of the American Embassy) was built during this period.
Many of the sculptures were also sold. The Italian Government bought its last 104 pieces in 1901, the year after King Umberto I was assassinated, and moved many of them into the already overcrowded National Museum at the Baths of Diocletian. (Some of those that weren't moved are still in various locations on the compound of the US Embassy.) When the Palazzo Altemps was opened in 1997 as part of the National Museum in Rome, the Ludovisi and associated collections finally found a worthy new display space.
The Altemps Museum is the National Museum's "Department of the History of Art Collection", and so the collections are arranged in a conscious attempt to illustrate how they would have been displayed by a 17th century antiquarian such as Cardinal Altemps rather than according to modern museum patterns. Everything is beautifully displayed with very good signage and with excellent diagrams in Italian and English in each room which explain not only the works of art but also why the early collectors thought they were worth collecting.
The building itself is also remarkably well displayed. Those interior frescoes which remained after years of neglect were meticulously restored, and some rooms are quite remarkable -- don't miss the "wedding gift chamber" which has a surviving fresco from the Riario period of the Palazzo depicting a display of the wedding presents given to Girolamo Riario and Caterina Sforza when they were married in 1477. It as been conjectured that some of the gifts, gold plates, ewers, and candlesticks in the fresco may have been used as collateral to finance the initial construction of the Palazzo. All of the various stages of construction on the site, from the ancient Roman marble-working shop through Medieval housing through the stages of construction of the palazzo are visible in openings through more recent walls and floors.
The courtyard, by Antonio di Sangallo the Elder, Baldassarre Peruzzi, and Martino Longhi (sequentially) is partially covered with a modern awning to protect its sculptures and friezes from the elements. A shell-mosaic fountain displays the Altemps coat of arms featuring the bridge over the Ems River that separated upper course -- "Hohen Ems" or "Alt Emps" -- from the lower. The fountain is on of the few authentic "Rococo" architectural elements in Rome. The loggia at the rear of the courtyard has frescoes from the end of the 16th century and busts of 12 ancient Romans, nine of whom are emperors.
The Palazzo's opulently decorated church is dedicated to St. Anacletus, an early martyred pope, and to the Madonna of Clemency. In a rare departure from the traditional practice of interring Popes either in St. Peter's of some other grand public church, the remains of the Saint are in the sarcophagus below the altar inside this private Palazzo,. The frescoes on the walls depict the beheading of Anacletus despite pleas of mercy from onlookers, a completely fictitious event made up by the Altemps family. The imagery is an obvious reference to the execution of Roberto, one of the illegitimate sons of Cardinal Altemps, who had been condemned and beheaded on the orders of the reformer Pope, Sixtus V for notorious adultery. Sixtus (Felice Peretti) was a man of humble origins, who, it was said, was trying to prove that his moral reforms would apply even to the high and mighty.
The Palazzo Altemps Museum obviously contains too much to catalog here, but luckily there is a museum bookstore just to the right of the museum entrance in Piazza S. Apollinare, a small piazza just a little north of Piazza Navona. There you can purchase the Palazzo Altemps guide (by the Soprintendenza Archeologica di Roma -- several languages including English), which is adequate for the casual visitor, or more detailed studies of the various collections and the structure. The Museum is open Tuesdays through Sundays from 0900 through 1945 (summer, 2200). The museum has clean restrooms, is only partially wheelchair accessible, and has no snack bar (but food is available in nearby Piazza Navona).
Altemps origins and History:
http://www.educando.it/sd/s&d/s_d1_2/altemps01.htm (in Italian) and
http://www.hurricane.it/castelliromani/frascati/mondragone.html (Italian), which also has the history of Cardinal Altemps' country Villa, Mondragone, in Frascatti, and
(See http://www.salzburginfo.or.at/rundgang/hellbrun_e.htm (English) for Salzburg's Hellbrunn Palace, built by another Markus Sittikus von Hohenems, the Archbishop/Duke of Salzburg and a nephew of Cardinal Altemps, as the Austrian equivalent to the water gardens at the Villa d'Este.)
Building and Collections:
The Altemps museum site: http://www.archeorm.arti.beniculturali.it/sar2000/p_altemps/home.htm
http://web.tiscali.it/romaonlineguide/Pages/eng/rbarocca/sBHy15.htm (English) from RomaOnline, and
Photos of the Palazzo and some of its most important statuary: http://www.siba.fi/~kkoskim/rooma/pages/PALTEMPS.HTM