After complaints from historic preservationists, the city of Houston is considering whether to ask that Texas Department of Transportation contractors halt work on Mecom Fountain.

The fountain, at the center of the roundabout where Main meets Montrose, is the rare, hard-edged modernist artwork that inspires love: Since 1964, brides and quince girls have braved traffic to use it as a portrait backdrop. It's eligible for the National Historic Register. And in December, then-Mayor Annise Parker signed paperwork to nominate the fountain as a city protected landmark, giving it the highest possible level of protection.

The fountain's nomination for historic status means that the Houston Archaeological and Historical Commission would have to sign off on any proposed changes to the fountain. So last week, architectural historian Anna Mod, a commission member, was dumbfounded to spot workers drilling holes to apply slabs of limestone to the fountain's base — the low cast-concrete wall that holds back the water that spills from its three concrete bowls.

It turns out, the limestone had been in the works for nearly seven years — long before anyone had planned to name Mecom Fountain a landmark, and an eternity in a city that only began protecting landmarks in 2005. The project had been approved by all the required government entities before the City of Houston historic protection kicked in.

THE CHANGES TO MECOM Fountain are part of Hermann Park's long-delayed Grand Gateway project. The latest in a series of much-praised park upgrades, the $4 million package of streetscape improvements is intended to improve pedestrian safety and to restore a sense of drama as one enters the park. In 2013, its designer, Houston landscape architect Kevin Shanley, compared the Grand Gateway to "the knocker on the front door of a wonderful huge house, a house of many rooms and so many things to do."

As part of that plan, the project would change the base of Mecom Fountain, cladding the low wall's base with limestone in a way that its designer, architect Eugene Werlin, didn't intend. And atop the low wall, the renovation would add a "bull-nosed cap" — a top something like a kitchen countertop with a rounded edge that would jut out over the wall.

That's not acceptable, say fans of modern architecture. The fountain was meant to have crisp modern edges, and was built with concrete, a material celebrated by mid-century architects. It's wrong to make the fountain look as though it belongs to the modern era, they say.

"'Suburban mall' is one of the complaints I've heard," says Margaret Wallace, the city's deputy director of planning.

"Obviously, we're concerned," says Steve Curry, president of Houston Mod.

"This alteration is overly decorative for the refined design of the fountain," Maverick Welsh, chairman of the city's historical commission, wrote Tuesday in a letter to the mayor and planning director. "In addition, it will change the sight lines for the beautiful water pools."

IN THE original Hermann Park design, from 1915, the fountain's site was a sunken garden, the beginning of a grand entrance to the park. But with the addition of slanting Fannin Street, the garden was cut off. And legend has it that cars frequently tumbled into the sunken garden.

In 1962, oilman John Mecom bought the hotel next to the garden. The Warwick (now Hotel Zaza) was already the playground of millionaires, but Mecom and his wife, Mary Elizabeth, proceeded to make it an even grander symbol of Texas excess: They filled it with paneling and furniture stripped from European palaces.

As part of that upgrade, the Mecoms donated $100,000 to redo the site of the sunken garden. For the center of the traffic roundabout, architect Eugene Werlin designed the fountain: three circular bowls set inside a low oval wall. The three bowls lined up with Main Street, on which the hotel was located — and was set at roughly a 30-degree tilt from Montrose Blvd., and the traditional entryway to the park.

In 1964, the Mecoms donated the fountain to the city of Houston. Soon after, Werlin designed an even more significant project for Hermann Park: Miller Outdoor Theater, whose swooping roof is a favorite of Houston architecture fans.

BECAUSE THE Grand Gateway project uses funds from the Texas Department of Transportation, the Texas Historical Commission was required to approve it. But the application is vague about the fountain, and Commissioner Linda Henderson says that if she'd realized the project included the fountain itself, not just the area around it, she'd have requested more information.

Now, the historic commission has asked that TxDOT halt its contractors. And it's not clear whether the city of Houston, whose Parks Department is leading the project, will follow suit.

"The city is still determining the best course of action for this project," Pat Walsh, director of Houston's Planning and Development Department, emailed Wednesday morning.

"There are no villains," says Doreen Stoller, executive director of Friends of Hermann Park. "TxDOT followed the letter of the law. Joe Turner (head of the Houston Parks Department) is trying to do the right thing. I really think everybody's on the same side. We all want preservation."

She pauses: "You know, it's exciting that people care."