There's a plaque on the campus of Northeastern Illinois University that refers to Abraham Lincoln as a Democrat.
Recently, a few websites noticed a plaque on the Frank Lloyd Wright Building, which houses Northeastern's Carruthers Center for Inner City Studies, that reads "This building is dedicated to public service honoring the memory of Abraham Lincoln - Democrat."
One could argue about how Honest Abe would more likely be in the Democratic party today, rather than the GOP. But that's only speculative, and the fact is Lincoln was the first Republican president of the United States.
But NIU isn't actually saying Lincoln belonged to the Democratic party.
The university explains that it's not meant to refer to any political affiliation:
The Carruthers Center for Inner City Studies at Northeastern Illinois University is housed in a building that bears historical significance. From time to time, the integrity of a plaque honoring the memory of Abraham Lincoln is questioned. Installed in the building for its opening in 1905, the plaque includes an inscription of the word "democrat" following Abraham Lincoln's name. According to building archives, the word democrat was used because Lincoln was an advocate for democracy—the political or social equality of all people. The word was not chosen to reflect a political affiliation.
Unfortunately, that explanation probably won't stop these people from freaking out on Twitter: