The latest phased reopening of sites will see Historic Environment Scotland (HES) unlock gates at more historic sites across the north and north east.
Broch of Gurness on Orkney and Bonawe Iron Furnace in Argyll re-open from Monday, May 24.
Spynie Palace in Moray is following suit.
Level 3 restrictions remain in place in the Moray area amid a surge of positive Covid test results.
Only one Covid case has been reported today and none were recorded in the two preceding days.
However, visitors should check Scottish Government travel guidance ahead of their trip.
In a later reopening phase, Dundrennan Abbey in Dumfries and Galloway and Edzell Castle in Angus can be visited on Friday June 4.
Bothwell Castle in South Lanarkshire, Elcho Castle and Huntington Tower in Perth, Kildrummy Castle in Aberdeenshire, and Maeshowe visitor centre on Orkney, will reopen on June 21.
The Maeshowe chambered tomb be closed due to Covid restrictions.
A heritage talk and interpretation will be available and should be booked online.
In addition, the re-opening of Dumbarton Castle and Rothsay Castle will take place on June 30.
The organisation’s chief executive Alex Paterson said it was a big step forward.
He said: “We are pleased to announce even more of our sites reopening up and down the country, providing visitors with the opportunity to enjoy much loved heritage attractions once again.
“We are opening a further 13 of our ticketed sites to visitors over May and June, including a number of seasonal sites.
“This joins over 70% of our attractions which opened at the end of April with additional sites to follow.”
The phased approach to reopening is hoped to provide “as diverse a mix of attractions as possible”.
Safety measures will be in place with face-coverings worn indoors and in enclosed spaces.
Tickets can be booked on the HES website.