The internet offers quite a number of splendid historical resources. I present here for your consideration a few that provide first source historical documents, along with a couple databases of historical maps.
A Papal Bull of Pope Urban VIII from 1637AD.
Yale's Avalon Project is a great resource, with a host of legal and historical documents listed by century. You can find it here
Yale Avalon Project
At Fordham University, several historical document sourcebooks have been assembled. While the particular slant and perspective of these collections is sometimes a bit odd (it is, frankly, difficult to tell that Fordham is Catholic from their site), there are still a number of worthwhile sources here. Three that I would recommend are:
Planisphæri cœleste, a 17th Century Map of the Constellations by Frederick de Wit.
This antique map resource is truly splendid, and a real delight to browse through. This has almost an aesthetic, rather than historical, focus to it. It is, appropriately named, Old Maps On-line:
Old Maps On-line
The University of Texas at Austin also presents a useful database of historical maps, this at their Perry-Castaneda Library Map Collection:
Perry-Castaneda Library Map Collection