San Marino, which as far as I know is known only for being very small,* is actually the oldest constitutional republic in the world.
Founded as a republic after breaking away from the Roman Empire in 301, San Marino is the oldest surviving republic in the world. Its constitution, adopted in 1600 is the oldest constitution still in effect.
A few other facts about San Marino: the official name of San Marino is Most Serene Republic of San Marino. A native of San Marino is Sammarinese. It is the smallest of the European micronations, but it is also one of the wealthiest European nations per capita. It has the lowest unemployment rate in Europe (though in fairness, when you only have 30,000 people, it’s not like that’s really a formidable statistic.)**
*61 km2 with a population of around 30,000. They also field a football team, but not a very good one. They’re currently ranked last (202nd) in the FIFA standings. Then again, there are fewer people in the whole of Liechtenstein (ranked 141st of 202) than were at the Scotland/Liechtenstein Euro Qualifier yesterday and Scotland (ranked 41st) still needed seven minutes of added time to pull out a win, so take that as you will.