Last year, when making a list of 10 great Romanesque buildings in Milwaukee, I couldn’t help but include the Federal Courthouse, 517 E. Wisconsin Ave., one of the city’s most visible – if not THE most visible – examples of Richardson Romanesque Revival architecture.

What makes the building especially interesting is the explosion of decoration on the exterior and interior. It’s an example of what U.S. Courts librarian Barbara Fritschel calls "Richardson on steroids."

What makes it a little bit more intriguing is that visitors must pass through security to enter and then are forbidden to take photographs. And that’s a shame, because it means very few Milwaukeeans get to see the explosion of color and detail and light that makes the interior as attractive as the exterior, which is clad in grey granite from Mount Waldo, Maine.

The building – erected in spurts between 1892 and 1899, as the federal government sporadically ponied up funds – was designed by the colorfully named Willoughby J. Edbrooke and is listed on the National Register of Historic Places.

Edbrooke was born in Evanston and got his start in Chicago, working with Franklin Pierce Burnham (no relation to Daniel, apparently). The two collaborated on the Columbian Exposition in Chicago and on some other high-profile works, notably the Golden Dome on the Notre Dame campus.

After splitting with Pierce, Edbrooke moved to Washington D.C., where he worked as supervising architect for the Treasury Department, for which he designed many post offices, court houses and other federal buildings. Among them was Milwaukee's courthouse, which Edbrooke, who died in 1896, never saw completed.

The addition on the back was constructed in two phases, mostly to accommodate post office needs as well as the arrival of the FBI in the building. The first five floors were completed in 1932 and three more were added in 1941.

For the second year in a row, it will be open during Historic Milwaukee Inc.’s Doors Open event – held in 2013 on Sept. 21-22. There will be guided tours of the exterior and visitors can visit the first floor and atrium. However, tickets – limited to 30 per tour – are required for tours of the interior.

Last week, Fritschel – who trains the docents leading the Doors Open tours – showed me around the building. We peeked into some courtrooms, spent some time in the atrium and wandered a bit more. To my disappointment, a climb up the tower, which had seemed permissible at first, turned out to be off the table, after the General Services Administration, which manages the building, nixed it.

The building – for which Edbrooke drew inspiration from H.H. Richardson’s Allegheny (Pa.) County Courthouse and Jail in Pittsburgh and which bears many similarities to Edbrooke's Old Post Office in Washington – opened in 1899 as home to the United States Courts – there was only one federal judge assigned to the area at that time and he was assisted by circuit court judges, whose purview then differed from circuit court judges today, said Fritschel. However, the largest tenant in the more than 300,000-square foot building was the U.S. Post Office, which occupied the area that is now the atrium floor.

Walking through the elaborately tiled foyer and into the glare of the five-story-plus atrium, with its sprawling skylight, we were standing in the former post office space. Rising to about the second floor is a steel frame that once was covered in glass. A walkway spanned that lower skylight, allowing postal inspectors to keep an eye on the post office employees below.

The post office remained in the building until a new one was constructed on St. Paul Avenue in the late 1960s. Afterward, the atrium floor was recast as an Internal Revenue Service office and the space was divided up into offices. When a heavy object accidentally fell through the skylight – no one was injured – the glass was replaced with a less-than-attractive opaque covering.

The IRS later moved into the Henry S. Reuss Federal Plaza, 310 W. Wisconsin Ave., built in 1983, and the atrium was restored as part of a major, seven-year renovation launched in 1989. The steel frame was kept, but left uncovered. So, really, we’re the first generation of folks to be able to stand on the floor and peer unobstructed up to the roof skylight.

While gazing upward, notice how the railings on each floor are unique. (Before you pass through security, try to find the artists’ names integrated into the decoration painted on the vaults above. Ask a security guard to give you a clue.)

And what a view it is, with more than two miles of ornate leafy decoration swirling around. Inside the building, exterior motifs are repeated. The dragon heads atop the dormers appear atop doorways, faces from outside pop up atop capitals, windows facing the atrium have Romanesque arches. In the 1999 Centennial Courtroom on the Jackson Street side, a shield motif reappears directly behind its exterior counterpart.

What the inside can boast that the outside can’t, however, is incredible oak woodwork throughout: doors, ceilings in the main stairwell and, above all, in the stunning Ceremonial Courtroom – the oldest of the 13 courtrooms in the building – which has a wealth of ornate detailing.

In addition to the millions of one-inch tiles that adorn most every square foot of floor in the building, There is a wealth of marble – and a fair bit of trompe l’oeil marble, too.

One of my favorite features in the building is the Directory board facing the elevator, just west of the main entrance.

Here you’ll find an interesting listing of the departments that once shared the building with the courts and the post office.

The second floor was an especially interesting place, housing steamboat inspectors, the IRS, the "Wine and Spirit Department" and the "Oleomargarine Department" (read this!).

Other floors were home to the weather bureau, the U.S. Inspector of Locomotives, the Bureau of Animal Industry, the U.S. Lighthouse Inspector and the Referee in Bankruptcy. Note that while the assistant custodian had an office, it appears his boss wasn’t so lucky.

Whether or not that’d be my favorite if I had visited the tower, I can’t say, but I did give Fritschel my card, asking her to file it under "tower" and to let me know if an opportunity to climb ever arises.

In the meantime, I’ll keep admiring its profile in the Milwaukee skyline.