Rimini is the no. 1 beach resort on the Adriatic Sea. It is part of a stretch of coast that runs from the Po Delta to Cattolica with lots of sandy beaches, nightlife and restaurants.
Of all the towns on the coast Rimini is the biggest and has most to offer. The city dates back to the 1 st century before Christ, and the Arch of Augustus is one of the monuments stemming from Roman times. In the historic centre you should also have a look at the Palazzo della Podest and the Palazzo Arengo, the Fish Market and the Fontana della Pigna. They are all located on the main square (Piazza Cavour). Other sights include the Castel Sismondo, the Roman Bridge of Tiberius, the Tempio Malatestiano, and the Museo Civico housing works from the fourteenth century Riminese school.
You can make some great day trips from Rimini. Florence, Bologna and Venice are within reach if you have a car. Ravenna with its great frescoes is just 30 km away. You can also visit the Republic of San Marino, 25 km west of Rimini. It is touristy and you might want to consider going to San Leo on the same road of San Marino: smaller, nicer and not so crowed of tourists.