The Welsh government has commissioned the study to improve the commercial performance of historical and culturally important places.
It is expected to report back to ministers by the end of March.
Baroness Jenny Randerson, who is leading the review, said Wales needed a more unified image of its heritage.
The Welsh Liberal Democrat peer added the fact that Wales is a small country had pros and cons in the promotion of its attractions.
"The disadvantage is that we don't have a vast number of tourist visitor sites, we don't have a vast number old houses, shall we say, in comparison with England," she said.
"But we do have huge quality and we have the advantage of being able to work closely together in a way in which it's difficult to do in a country as big as England."
She added it was "vital that our heritage organisations work closely together to maximise our cultural influence and the success of our tourist industry".
Baroness Randerson was appointed parliamentary under-secretary of state at the Wales Office in 2012 and her portfolio includes culture and tourism.
She was minister for culture, sport and the Welsh language in the Welsh government from 2000 to 2003.
A review of heritage attractions will help Wales compete with the other UK nations, the peer who is chairing it has said.