Buckhead's newest trophy office tower is close to another office deal.

Global insurance giant Aon is in final negotiations to lease between 65K and 70K SF in Three Alliance Center, sources familiar with the deal tell Bisnow. That means Aon will be vacating its offices at Piedmont Center North — part of the Piedmont Center office campus — where it occupies some 60K SF.

The new Three Alliance lease should not affect Aon Hewitt's operations at Riverwood 100 in the Cumberland/Galleria submarket, sources said.

The deal caps a lengthy search for Aon, during which it had considered numerous office buildings in Buckhead and in Central Perimeter, including Three Glenlake, the former home for the headquarters of Newell Rubbermaid. Officials with JLL, which represents Aon, did not return calls seeking comment, and officials with Tishman Speyer, the owner of Three Alliance, declined to comment.

But for Tishman Speyer, Aon is another feather in the leasing cap of Three Alliance, which started construction without having any office leases signed. As the tower rose, Tishman Speyer grabbed high-profile deals, including Global Payments, which inked a deal for three floors, moving its headquarters from 10 Glenlake in Sandy Springs; CBRE, which is moving into some 100K SF; and State Street Corp., which is taking 34K SF.