Clava Cairns would be top of my list. They are about 6-7 km east of Inverness. There is a large car park and free access anytime. They are best photographed early morning or evening as the light is better then. They are also quieter then as they can get busy as they they have been made famous by the TV series Outlander.
My other favourite place to visit is Fort George, which is a bit further - 20km north east of Inverness. This was built after the Battle of Culloden to control the Highlands and crush any future Jacobite rebellions. By the time it was finished (late and well over budget) the Highlands were relatively calm and it never saw any military action. There is a story, maybe apocryphal, that one shot was fired by a jittery soldier on night duty who thought he saw a Jacobite soldier creeping up to the fort and fired at him. Next morning the guards found the dead body of a cow....The fort is still used by the military and soldiers are seen around the site.
It is an amazing structure with ramparts and ditches and would have been invincible. It juts into the Moray Firth with views across to the Black Isle. Bottle nose dolphins are often seen from the ramparts.
There is loads of information and photos here. You do need to allow at least two hours for a visit and maybe longer...
The other alternative would be to stop off at the ruined Urquhart Castle, near Drumnadrochit on the banks of Loch Ness. It is popular with visitors because of the Loch Ness Monster story...
Lots of pictures here