The current library has been in its location for more than 60 years, according to the report. The original structure was built in 1957, and there were remodels and additions in 1967 and 1991.

If the City Council does not accept the money, staff say, generating this kind of revenue could take up to 10 years to gather input, plan fund and build the project.

Rebuilding the main library is expected to cost $45 million, according to a study by architectural consultant group Noll and Tam . The city would be expected to pay the initial $20 million and costs associated with staff or consultant time, according to the staff report .

John Arrillaga has offered $25 million to the city of Menlo Park to rebuild its main library, according to a staff report released Thursday, July 13. Mr. Arrillaga is a local real estate billionaire who has made numerous large donations to Stanford University and in the past donated to Menlo Park to rebuild the gym and gymnastics center.

The Menlo Park library has been an institution in the city for over 100 years -- since 1916, while its current home has been in the city's Civic Center since 1957. It was previously housed in a school, a hotel and the current BBC Building (formerly City Hall.) (Photo by Kate Bradshaw/The Almanac.)

The city could finance the $20 million over a 15-year or 30-year term, or may consider other financing ideas, pending feedback from the city's Finance and Audit Committee.

The project could also have "significant ripple effects" and delay other projects city staff are working on. That includes projects like addressing housing programs, reviewing the downtown/El Camino Real specific plan and adopting more stringent requirements for electric vehicle chargers, staff say. The library project could also add delays to city capital improvement projects that have been budgeted for but not started yet and slow staff's capacity to process the transportation and engineering aspects of development projects.

"Mr. Arrillaga's expectation is that the City expedite their portion of the timeline to the extent possible. Additional time could affect the offer," the report says.

When Mr. Arrillaga funded the gym and the gymnastics center in the Menlo Park Civic Center, it took about three years to go from the council approving the donor's offer in 2008 to completing the first building. However, those plans had been farther along than the library is now, staff noted.

Ms. Bramlett said she thought the donation was "wonderful" and "generous" but noted that the commission doesn't plan to neglect its focus to establish a new, modern Belle Haven library branch.

In March , the results of the space-needs study for the main library were presented to the council. Several council members directed library staff and commissioners to prioritize work toward improving the Belle Haven branch library at least concurrent with plans to rebuild the main library in the Civic Center.

Currently, the Belle Haven library housed on the campus of Belle Haven Elementary School, contains primarily children's materials and is open during very limited hours. The city has budgeted money to extend its weekend and evening hours, pending hiring staff, according to Ms. Holmer.

Initially, it seemed that establishing a more robust library in Belle Haven would be the commission's priority, she said. Then, the city's library director, Susan Holmer, announced at the meeting that an anonymous philanthropist would be giving a sizable amount of money that would be a "considerable portion toward the overall cost" of rebuilding the main library in the Civic Center. That offer, she said, should be factored into the commission's work plan.

Library commissioner Lynne Bramlett said that the Arrillaga proposal had been discussed at a special Library Commission meeting held Monday night, July 10. The purpose of the meeting was to prepare a library work plan update for the council.

There are many children who live in Belle Haven, most of whom, she said, "are forced to attend a school district that lacks resources. All children and adults need to have access to resources. A library is that resource."

Cecilia Taylor, a Belle Haven resident who ran for City Council last year and has been active in the community organizing activities since then, had stronger words. "How could a (philanthropist) fail to address the portion of Menlo Park that does not have an adequate library? ... Why rebuild a castle in (an) affluent community that has a plethora of resources?"

"There is a great ... disparity, if you will, of city facilities," she said, referring to the difference between central Menlo Park and Belle Haven. "(Belle Haven) is really taking the brunt of all new development," she said.

"I would never look a gift horse in the mouth," she said "We're grateful for it, but we're not going to forget about Belle Haven."

John Arrillaga offers $25 million to rebuild Menlo Park's main library in Civic Center