As we noted back in April, planners got inspiration from the neighborhood’s architectural history and gay heritage. Some of the features include new sidewalk trees (ginkgo and king palm), multicolored street lights and a mini-plaza in front of what used to be Harvey Milk's camera shop, which is now a Human Rights Campaign store.

The sidewalks will be widened from 12 to 22 feet, and narrower lanes are expected to calm traffic. A “Rainbow Honor Walk” will feature LGBT pioneers, including Milk, Allen Ginsberg, Oscar Wilde, James Baldwin and Harry Hay.

At Thursday's groundbreaking, the Castro Community Benefit District announced that parallel rainbow stripes had been chosen to grace the crosswalks at 18th and Castro streets.

Not everyone in the neighborhood is crazy about the design, but it was the favorite among 4,500 votes cast online and in person, said Andrea Aiello, director of the benefit district.

Some merchants, meanwhile, are worried about the disruption the eight-month construction project will bring. "We're super, super excited about the end process. We're really, really worried about the process itself," said Terry Aston Bennett, president of the Merchants of Upper Market and Castro.

Wiener said city officials and the contractor, Ghilotti Bros., Inc., would do everything possible to minimize the impact. The end result, he said, would be worth it.

"We're going to have very strong liaison relationships between the contractor and DPW and the merchants to make sure things are cleaned up properly and make sure that our concerns are addressed," Wiener said.

"We'd like to do it without inconveniencing shop owners, but you know, this stuff lasts for 20,30, 40 years. If we have to do this once every quarter-century it's not too bad," said contractor Mike Ghilotti.

Aiello said the benefit district got a grant to help merchants deal with the disruption, but they decided to use it for a new ad campaign that will be featured on Muni buses, the F-line historic streetcars and at three East Bay BART stations.

"The theme is: It's hard work being beautiful. We're under construction but still open for business," said Aiello, who encouraged visitors to use public transportation. The Castro, she pointed out, is well served by Muni. Buses will continue to run on Castro Street during construction.

Work along the two-block stretch of Castro Street between Market and 19th Street is expected to last until October. The first block between Market and 18th is expected to be completed by mid-June, when crews plan on taking a break for Gay Pride. Construction will resume in early July.

Castro StreetCastro Street

San Francisco Breaks Ground on Colorful Castro Street Redesign