There are a few notable Lincoln Memorial proof varieties, including the 1979-S and 1981-S Type I and Type II proofs. The 1979-S Type I "S" mintmark has a blobby appearance while the Type II shows a more clearly defined "S". The 1979-S Type II "S" constitutes the 1981-S Type I "S", with the 1981-S Type II "S" showing a very clear "S" with bulbous serifs. As for great rarities, there are few among the Lincoln Memorial proofs that come close to the fame of the 1990 no-S proof, a coin that spawned many headlines in the early 1990s and is considered a popular and rare modern-era proof error. Production of Lincoln Memorial proofs ended in 2008 with the closure of the series.