And some history there is, considering that you're talking about the world's oldest republic. If you're looking for stats, it's also the third smallest state in Europe (after the Vatican City and principality of Monaco) and, as an enclave within Italy, it's not surprising that its c17,000 inhabitants speak the Italian language, are allied to Italian social, foreign and economic policies, eat Italian food, use Italian Euros (although they have cannily minted a collection of limited edition sets of their own to flog on to numismatists at an enormous mark-up -- see entry above).
Tradition has it that the place is named for a Christian stonecutter from Dalmatia called Marino who took refuge in the very early 300s on Mt. Titano in central Italy not far from Rimini -- Titano is now the main geographical feature of present-day San Marino. The Saint's bones are allegedly to be found in the reliquaries of various churches (see entry below) which also date back several hundred years. By the mid-5th century, a community was formed which, because of its relatively inaccessible location, bar a few brief interruptions it has managed to maintain its independence, whose recognition in Europe was led, in 1631, by the papacy. In 1849, the republic gave refuge to Garibaldi, the Italian patriot and soldier, but got few thanks for it although Italy and San Marino later signed a treaty of friendship and economic cooperation in 1862 (which has been renewed and expanded several times). As suggested above, the people of San Marino are closely allied to their more powerful neighbour, fought alongside their troops in WWI and WWII, so much so that Allied aircraft bombed the republic in 1944. Following a decade of post-war Communist rule, a coalition of Christian Democrats and Social Democrats came to power. 1960 saw female enfranchisement followed, in 1973, by the granting of the right to hold public office. San Marino joined the UN in 1980.
It's obvious from this that there is 700 years of history here and history buffs will expect some serious olde worlde architecture and quality antiquities. Though small-scale, you won't be disappointed, starting (provided you've organised a parking-place up front) with entry into the old city centre via the "Porta San Franceso", an ancient guard-post dating from 1361 (the alternative if you're coming by car and haven't organised parking in advance is to drop your car off at the car park at the base of the cable-car which connects Borgomaggiore to San Marino city -- signposted as soon as you enter the republic).