The steel structure of the building known as Plaza House is beginning to take shape.
Plaza House sits behind Trafalgar Court, which is on the seafront, and alongside the Premier Inn and Good Rebel restaurant.
The building will be six floors high and provide 67,000 square feet of office space.
60% is already let, to IQEQ, Intertrust, Artemis and BDP.
Jo Watts of Watts Property, who are the letting agents, says it's proving popular:
“With no other large floor plate office buildings in the development pipeline for the foreseeable future and firms wanting to provide their staff with the best accommodation possible, we are confident the remainder of the space will now be taken up quickly.”
Developers Comprop describe it as the 'centre piece and final part of the Admiral Park jigsaw that forms the heart of Guernsey’s financial services district.'
MD Steve Marie says its completion will have spanned two decades of construction:
“We are proud of all the developments on the site; and this final piece of the jigsaw will see the culmination of Comprop’s significant investment in this site and a celebration of all the hard work of the Comprop team, our agents and contractors over the years.”
They say it'll be Guernsey's first BREEAM rated building, which is an internationally recognised sustainable building certification.
Completion is scheduled for the summer of 2024.

Memorial service for sailors who perished off Guernsey's west coast
"Catastrophic" engine failure stops Channel Island ferry
Popular Guernsey swimming pool could re-open within days
Fog causes major disruption at Guernsey Airport
Sark chef creates astronomy app
More women cycling in Guernsey after confidence booster classes
Toilet leak forces closure of popular Guernsey seawater pool
Alderney Children's Centre shortlisted for Nursery World Award