CED suggests that holy places such as temples and churches can be referred to as sanctuaries.
To describe places of historical significance, perhaps you can use the word monuments.
an obelisk, statue, building, etc, erected in commemoration of a person or event or in celebration of something
a notable building or site, esp one preserved as public property
a tomb or tombstone
A little suggestion for your app that you may find useful:
you can create a special section called the UNESCO World Heritage Sites
where you can have places that are listed by the UNESCO (United Nations Educational, Scientific and Cultural Organization) as of special cultural or physical significance.
Here is a link to the list.