States say visitor numbers are up 7% on the 2024.
Castle Cornet, Fort Grey and the German Signals HQ close this weekend for the '25 season.
The exception is the Castle, which will be open on Remembrance Sunday between 10am and 1pm.
A drop in cruise ship visits dented visitor numbers to the Castle but the States say increased French day trippers compensated for this.
On the 80th anniversary of the Liberation, visitors to the German radio command bunker at St Jacques rose 20%.
Looking back on the season, Guernsey Museums' Helen Glencross says it's been positive:
"We’re delighted to see such strong engagement from both local people and visitors.
"The popularity of events like Castle Nights and Twilight Cinema shows how much these historic sites mean to the community.
"In addition, the rise in French tourism is a really positive trend, and we’re looking forward to building on that success."
More than 250,000 visitors to Guernsey in 2025
First Michelin star awarded in Guernsey in more than a decade
Guernsey Fire & Rescue Service needs "investment and modernisation"
Engine room fire onboard DFDS freight ship
Gannets return to Alderney
Burglaries at Guernsey pharmacy and garage
Kids fly free between Guernsey and Jersey this half-term
Guernsey Water to take over cesspit collections from States Works
