BALTIMORE -- The building crouches gray and anonymous, hemmed in by other structures along Baltimore's narrow streets. Its vast dimensions are almost indiscernible, the rich detail of its interior unknown to many who pass it every day.

It is the Baltimore City Circuit Courthouse, a turn-of-the-century Renaissance-style fortress once praised by Baltimore's jaundiced journalist emeritus H.L. Mencken for its "solemn grandeur."

But much of that grandeur -- sweeping marble halls, mosaic emblems, towering columns -- is now invisible, cut up and covered over to make space for more courtrooms, clerks' offices and a drab clutter of other facilities as the city and the burden of its court have grown in the past 87 years.

Now court officials hope to reverse all that and unmask the building's former elegance with an ambitious $35 million, eight-year restoration program that officially got under way in 1984 but has gathered momentum only recently.

A downtown landmark, the building stands at North Calvert and East Fayette streets, its main entrance topped by a loggia with eight 35-ton, 31-foot-high Ionic columns, the largest monolithic, or single-piece, pillars in the world, according to court histories.

The building was rededicated in March 1985 as the Clarence M. Mitchell Jr. Courthouse, after the longtime Baltimore civil rights leader.

The building, which opened its doors in January 1900, was changed most notably in a 1950s-era splat-and-spackle splurge in which contractors sandwiched in three more floors between the original three, filled in a central courtyard and covered over decorative windows, skylights, stone floors and marble walls with a deadening veneer of acoustical tile and industrial grade linoleum.

Slowly, room by room, tile by tile, the veneer is being ripped out and new life breathed into the building.

"The 1950s was an ugly period," said the court's administrative judge, Joseph H.H. Kaplan, prime mover of the restoration effort. "Look at this," he grumbled, peering down a dimly lit, low-ceilinged hallway. "I call it 'early motel.' "

Even with the extensive renovations, the additional floors and office spaces of the 1950s will have to remain, unwanted necessities of court growth.

While restoration costs will run as high as $10 million, Kaplan said, the bulk of the $35 million project's cost will be in replacement of heating, air conditioning and other electrical and mechanical equipment.

If Kaplan has his way, restoration of the building, which covers an entire city block, will be completed in the early 1990s.

The city has spent $1.2 million, he said, including $250,000 to restore two stunning stained-glass domed skylights that were smashed and then boarded up in the 1950s.

The original skylights, crafted by the New York glassmakers Heinigke & Bowen in 1899, were painstakingly replicated by another New York firm, Rambusch Studios, from a turn-of-the-century photograph and a few random shards of the original glass found recently by workers in the well of one of the skylights.

The skylights depict eight classical female figures representing the Virtues: Justice, Truth, Mercy, Religion, Logic, Courage, Peace and Literature.

Another restored area of the building is the criminal court lobby on the second floor, a spacious room featuring ornate balustrades on two sides and 16 reddish Numidian marble columns supporting the 25-foot-high ceiling.

Large murals fill the walls, depicting Maryland colonial governor Leonard Calvert concluding a treaty for the purchase of land for European settlers in 1634.

Other restored areas include the 130,000-volume Baltimore Bar Library, the mahogany-paneled orphans court (now a museum of legal history) and the "Supreme Bench" courtroom, a large circular room supported by rare Sienna marble columns from the Vatican quarries near Rome and topped by a high-domed coffered ceiling festooned with dozens of bas-relief florets.

Accounts at the turn of the century said that despite the near depletion of the Vatican quarry, Pope Leo XIII consented to its use for the courthouse after pressure was brought by Baltimore's Cardinal James Gibbons.

The courtroom, originally occupied by the 12 Supreme Bench judges of the circuit for ceremonial and other occasions, is now used by Kaplan for everyday court business.

Much of the litigation resulting from Maryland's savings and loan crisis of 1985 has been hashed out there under Kaplan's supervisory eye.

Numerous other courtrooms, hallways and lobbies are scheduled for restoration, as is the outside of the building.

While its exterior granite and marble walls are strong and appear generally clean (they were sandblasted in 1974), window frames are rotting and have not been painted in 20 years. Decades of pigeon droppings cover many balconies and pillars and must be removed.

Kaplan said he hopes the $35 million restoration job will be financed primarily by $25 million from bond issues and other public sources, but he is relying on $10 million in private contributions. To that end, a special Baltimore Courthouse and Law Museum Foundation, headed by an array of the city's legal elite, was formed recently to begin soliciting tax-exempt contributions.

A second, newer court building across Calvert Street from the original courthouse also is slated for about $27 million in renovations, Kaplan said.

"But," he added, patting the walls of the original building affectionately, "this is my baby. The other building is not an orphan. But it doesn't have the grand spaces of this one."