Now Rubenstein Co. must fill more than a million square feet of space, without weakening the area's ability to command high rental rates. The Rubenstein Co. turned heads in the real estate industry three years ago when it bought the big Wyeth-Ayerst Pharmaceuticals Inc. campus in Radnor.

The complex deal, which it won after serious competition from other bidders, was a significant test for the family-owned firm headed by Mark and David Rubenstein.

Adding Wyeth properties to the nearby Radnor Corporate Center, which Rubenstein purchased a decade ago, was "like buying Park Place and Boardwalk in the old Parker Brothers Monopoly game," said Judson Wambold of Tactix Real Estate Advisors.

It now has the only office real estate monopoly in the Philadelphia region. There is only one other multi-tenant office building in the sub-market, Berwind Property Group's Radnor Court, and it is almost fully leased.

So if you want your office to be in Radnor, you have to deal with Rubernstein. And brokers say many do want to be in Radnor. "The demographics are through the roof. That's where the CEOs and CFOs live," said Timothy Mahoney of the Mahoney Reality Group.

Because executives can slip away to children's soccer games and be back soon, Radnor has been able to command rental rates of more than $30 a square foot a year - $5 to $10 higher than for other parts of the region.

Now comes an even bigger test for Rubenstein than buying the property: Can it fill more than a million square feet of office space in what is at best a recovering commercial real estate market? And can it do it without weakening Radnor's ability to command high rental rates?

Some say yes. Others say maybe.

The big marketing push begins this month with invitations to brokers to visit and a new DVD extolling the virtues of working in Radnor. Three shuttle buses that link Rubenstein's buildings with transit stations and lunch spots declaring that Radnor "is at the intersection of business and life."

With more than 2 million square feet in the prime Ranor sub-market - the equivalent of both Liberty Place skyscrapers in Center Ciy - keeping the rental rates high is critical.

Rubenstein is jointly promoting the Wyeth campus, the renamed Radnor Financial Center - a 58-acre office park that it bought in 1994 from the real estate unit of what is now Sunoco Inc.

The challenge will be huge, many brokers say.

Conshohocken and West Conshohocken, not far away, have high vacancy rates - approaching 30 percent. That sub-market has gleaming new office buildings that are cutting rental rates to well below Radnor's.

In contrast, the Wyeth campus is a 1970s development, Mahoney said. "Suburban office tenants want to see trees and bunny rabbits. They don't want to look out at an interior atrium," he said, referring to the largest complex on the old Wyeth caompus.

For those who want trees, birds and bunnies, Rubenstein has the Radnor Corporate Center, which is it sprucing up with new lobbies and cleaned exteriors.

At the Radnor Financial Center, it touts a more energetic urban feel. The atrium of the complex has been redesigned to appeal to those who want "downtown without the hassles," said James Paterno, president of the Rubenstein Brokerage Group.

That atrium has a big electronic sign streaming stock quotes and a jumbo television screen, akin to New York's Times Square. High-tech directional speakers let viewers in designated spots hear the sound from the business programs on the big TV without blaring at those walking nearby.

So with the corporate center and the financial center, Rubenstein is trying to accommodate both the traditional suburban preferences and what it and others see as an emerging desire for an urban feel in suburban locales, Paterno said.

Steven J. Cousart of the CB Richard Ellis Inc. real estate firm, who leases space in Rubenstein's only rival Radnor Court, touts Radnor's location. He said it is:
- Served by both the SEPTA R5 and R100 commuter rail lines. It is one of the few stops with office space on the R5, the transit agency's premier line.
- Near the Villanova/St. David's exit on the Blue Route, so employers can draw talent from a wide area.

Still, Rubenstein faces a big challenge, Cousart said. "They need to lease a lot of space. They'll have to figure out a balance between lowering the rates to lease faster and keeping the rates high," he said.

Rubenstein is a privately held company and will not disclose the details of its purchase from Wyeth, which has moved to a $600 million facility in Upper Providence Township, Montgomery County.

Others in the industry say it was smartly structured so Wyeth kept paying rent for a time, easing the pressure.

All Paterno will say is: "We avoided the need to buckle under market pressure or scrimp on amenities. ... we're going to go slow and do what makes sense on the long term."

James Dugan, the Rubenstein vice president in charge of the project, said rental rates have come down only slightly, "from the low $30s to the high $20s," referring to the annual cost per square foot.

To ease financial pressure, Rubenstein sold 280 King of Prussia Rd., a 66,6180-square-foot office building at the edge of the campus, in December to Schiffrin & Barroway L.L.P., a Bala Cynwyd law firm specializing in class-action litigatiorr, for an undisclosed price.

The firm will use the entire building itself, so Rubenstein made the sale without bringing a rival landlord into Radnor.

Rubenstein also has leased a major portion of the former Wyeth research center to Centocor, a unit of Johnson & Johnson, of New Brunswick, N.J. "We're not actively marketing the balance of that space," Dugan said. "We would like to accommodate the anticipated growth of Centocor."

It also is not aggressivel marketing the six-story glass building at 555 Lancaster Ave. at one of the main entrances to the campus, hoping to land a major user later or sell it to a firm that would use the entire building.

A vacant building once leased to the PennDOT district office is also on the back burner. That building, adjacent to the Radnor-Chester Road entrance to the campus, will be demolished or given a new look, Paterno said.

The big push beginning this month is focused on 150-Radnor-Chester Road, which is six buildings. It had been built as a retail mall, and once was occupied by Sears Robuck & Co. The six structures are linked by a glass atrium, which will feature sidewalk cafes and other amenities. "It will be like downtown, but with the security of the suburbs," Paterno said.