Presenting multiple calendars in SharePoint

Hi! I have a challenge. 

We have one calendar for each meeting room, presenting when they are vacant and booked. These calendars are open within the organization, enabling everyone to see when the room is available. 

I want to include an overview of available rooms on our SharePoint site by gathering the schedule from, say 10 rooms, and presenting them in an "available today" view, either side-by-side or as overlay. 

When creating a SharePoint calendar (from Lists), I'm only getting other lists as available sources. Is there a way of including other calendars from Active Directory? It's so easy to do in Outlook, but in SharePoint I'm stuck! 

Thank you for all contributions!