The old federal courthouse in Lower Manhattan, whose courtrooms once held the Rosenbergs’ espionage trial in 1951 and, more recently, the Martha Stewart trial, is about to receive its first facelift since it opened 70 years ago.

The $227 million renovation will close the courthouse this September, and will force nearly two dozen federal judges who hold court in the building to crowd into temporary chambers in the nearby Daniel Patrick Moynihan Courthouse.

The construction of the old courthouse in Foley Square took only three years during the Great Depression, but builders say they will need four years to gut the infrastructure without damaging the historic exterior of the landmark.

Although the courthouse’s 26-floor tower, which ends in a gold-tiled pyramid, makes for a stately sight, those who work inside the building say that the interior has grown decrepit in its old age. In the upper reaches of the tower, judges go about judging amid leaking ceilings, mildew, and the occasional burst water pipe.

The 30th floor has been abandoned due to water damage, the district executive of the 2nd Circuit Court of Appeals, Karen Milton, said. On that floor, amid piled boxes, one of the few items in place is a small sign from a past era, reminding those present against entering the elevator with a lit pipe or cigar.

On the 25th floor, the courthouse library room has succumbed to leaking. Eight floors beneath that, a water pipe burst several years ago, flooding a judicial robing room in 18 inches of water. In the chambers of one judge, whom Ms. Milton declined to identify, a plastic water chute stretching from a leaky ceiling to a waiting bucket is a regular fixture.

Even amid the flooding and leaks, drinking water has to be carted in from outside. For years, the building’s drinking fountains have been wrapped in clear plastic, following concern that the lead and copper of the piping is leaching into the water.

In all, Ms. Milton estimates that at least 20% of the building is uninhabit able due to leaks, mold, or lack of temperature controls. Central air-conditioning is limited to the building’s base, leading to temperatures in the tower that can overpower the window air-conditioning units that dot the landmark’s exterior.

The 718,000-square-foot courthouse opened in 1936, only months after the Supreme Court building in Washington. The same architect, Cass Gilbert, designed both courthouses. The courthouse in Foley Square, which President Bush renamed after Thurgood Marshall, headquarters the 2nd Circuit Court of Appeals. Several trial judges for the Southern District of New York are also based in the Foley Square courthouse, although many moved in 1995 to the abutting Moynihan Courthouse.

The coming renovations will force 23 judges from their courthouse to the less amenable, sheetrock-lined chambers that, Ms. Milton said, were recently built for them on three floors of the nearby Moynihan courthouse. Visiting judges, who come into Manhattan to sit on appellate panels, will now share chambers in the Moynihan courthouse.

Leaving behind the old courthouse, whose central lobby directory still bears the name of several deceased judges, will not be easy for many of the jurists.

“There are mixed feelings,” the chief judge of the 2nd Circuit, John Walker, said during a telephone interview last week. “This is an important renovation that will make this building usable for much of the forthcoming century before another renovation is needed. But it is a dislocation. For senior judges, quite a percentage of the remainder of their lives will be spent in temporary chambers.”

The courthouse will be vacated by September, although it will start becoming quieter in late June, when the 2nd Circuit stops hearing appeals regularly for summer.

Since 2001, shortly after he became chief judge of the circuit, Judge Walker has been the driving force working to secure money for the renovations.

A spokeswoman for the government’s General Services Administration, Renee Miscione, said the entire project comes with a $227 million price tag – a sum that is nearly equal to the original price estimate of the nearby Moynihan courthouse. Construction costs for that courthouse and a neighboring office building ballooned to $1 billion, prompting a U.S. Senate committee to issue a report that examined the costs and lavish details associated with courthouse construction.

The government’s project engineer for the Foley Square Courthouse, Alan Berman, said the challenge of the renovation project lies in rebuilding the majority of the infrastructure without altering the building’s surface. The renovation will also provide an opportunity to wire the courtrooms for laptops and for displaying electronic evidence exhibits.

The first phase of construction will be largely devoted to repair work and to repointing the mortar on the courthouse’s exterior. The project’s second phase will involve replacing the building’s piping and wiring, and installing a central air-conditioning system throughout the tower. The architectural firm Beyer, Blinder, Belle received a contract in 2004 to lead the design team.

With actual renovation costs of the project’s two phases expected to run $160 million, the price tag of the renovated courthouse comes out to about $223 a square foot.

“As a rule of thumb, if you’re doing work on a historic building it can be as expensive as new construction,” a consultant on courthouses and a former official with the federal administrative office of the courts, Gerald Thacker, said.

The renovations are slated to conclude in July 2010. The renovations will not only affect judges, but also the more than 100 members of the support staff who work in the Foley Square Courthouse. For them, too, the landmark has become a source of pride.

A courthouse guard with the U.S. Marshal’s Service, Joseph Ribaudo, knows a long list of historic cases tried in this courthouse. As he discussed the upcoming move to the Moynihan courthouse at 500 Pearl St. last week, he rapped his hand on a marble wall in the courthouse lobby. The marble in the lobby and the surrounding corridors was quarried from six different states.

“If you touch the marble here and touch the marble at 500 Pearl St., you’ll feel there’s a difference,” he said.