Ask HN: Map services that offer historical tiles?

I have a growing dataset of historical archives that I'd like to project onto a map, but not today's geographical maps. Some of this data goes back hundreds of years. I'd like to avoid plotting something that happened in "New Spain" over modern-day Mexico. Place names just wouldn't make sense.

I'm having a hard time finding tile servers that offer historical geographies. In fact, it would be great to get maps as far back as hundreds of years even if they aren't detailed. It would be great to have the basic approximated country/region borders with the major names around the globe.