OSTIA ANTICA, Italy The ruins of Ostia, an ancient Roman port, have never captured the public imagination in the same way as those of Pompeii, perhaps because Ostia met with a less cataclysmic fate. Yet past archaeological digs here have yielded evidence of majestic public halls and even multistory apartment buildings that challenge Pompeii's primacy. Now officials hope that the decade-long restoration of four dwellings lavishly decorated with frescoes will focus new attention on this once-bustling port about 15 miles west of Rome. Last week the second-century insulae, or housing complexes, were presented to the public through the European Heritage Days program, in which each member country of the Council of Europe promotes new cultural assets and sites that have mainly been closed to the public. "Over all, this is the most important ensemble of second- and third-century frescoes in the world," Angelo Pellegrino, the director of excavations at the site, now called Ostia Antica, said in an interview. At its peak in the second century, Ostia sat at the mouth of the Tiber and served as the main shipping point for goods traveling to and from Rome. (Over the centuries deposited sediment has caused the ancient town to recede several miles inland.) Prosperous Ostians liked to embellish their homes, and traces of art have emerged on crumbling walls around the site. But the frescoes in the insulae are among the best preserved, officials say. Ethereal floating figures dance against a red backdrop in the House of Lucceia Primitiva. (A graffito with that woman's name was recently uncovered in the dwelling.) The nine Muses hold court in a house that bears their names; a small, erotic panel decorates what experts say was probably a bedroom in the House of the Painted Vaults. "They're exceptional indicators of the emerging merchant class and the economic and political well-being of the city in the second century," said Flora Panariti, an archaeologist who participated in the restoration. Stella Falzone, an expert in mural painting at Sapienza University in Rome, described the dwellings and their decorations as "a reliable mirror of Rome" during that period, especially precious for archaeologists and art historians because so little from that era survives in Rome. Popular colors of the time, red and yellow, dominate the House of the Yellow Walls, for example. "It's no coincidence that these are the colors of the Roma soccer team," Ms. Panariti said. Unlike Rome, which cannibalized much of its heritage over the centuries, or Pompeii, which was buried in volcanic ash in A.D. 79 and was not systematically excavated until the 18th century, Ostia remained mostly untouched until the early 20th century. The multistory dwellings were first excavated in the 1960s, but work stopped when the archaeologist leading the dig left for another job. They remained largely unknown to the public and to many scholars until archaeological administrators at Ostia Antica resolved to recover them. The buildings, in the western part of the ancient city, were built around A.D. 128 in a housing boom during Emperor Hadrian's reign. With demand for accommodations growing, new multilevel homes resolved issues of space and expansion. Although only the ground floors remain, evidence that buildings stood taller than one story has emerged from the rubble. If it weren't for Ostia Antica and its multistory houses and apartments, "it would be difficult for people to imagine how people lived in that era," said Norbert Zimmermann, president of an international association for ancient mural painting. Like Pompeii, Ostia Antica faces problems common to many of the sprawling archaeological sites in Italy. Money is scarce, the site is understaffed, and surveillance is spotty. But the biggest challenge here is high humidity resulting from the high groundwater level. "We try to dig as little as possible nowadays, because we can barely deal with caring for what's emerged," said Mr. Pellegrino, the excavations director. It took nine years to restore the four buildings, he noted, in an effort that was possible only because of a private donation of about 150,000. In the House of the Painted Vaults Ms. Panariti pointed to a delicately painted human form high on a wall. "These figures are disappearing again even though they were only restored two years ago," she said sadly. Humidity has forced conservators to detach many frescoes from walls and transfer them onto panels before returning them to their original locations. "It's necessary, but it causes immense sorrow whenever we have to do that," Mr. Pellegrino said. Only a limited number of visitors will be allowed to tour the four dwellings, and reservations are required. (Officials have not worked out the details.) Ostia Antica has not given up all its secrets. On Friday, in a different section of the ancient city, students were cleaning colorful frescoes in the House of Jupiter and Ganymede, named for the chief Roman god and the Trojan prince he anointed as cup bearer. "We're constantly restoring the site," Mr. Pellegrino said, "as long as we can afford to."