Gibraltar, Gibraltar
All the reading I had done on the Schengen rules indicated that they might not check but they might so you definitely want to leave the Schengen countries before the 90 days are up. Gibraltar is owned by the UK which means it is out of Schengen, so on the 90th day I crossed over into Gibraltar - and all they had at the border was someone glancing at your passport as you held it out and walked past. So I circled back and said I needed a stamp because of Scheng...