Leiden is a very charming university town, halfway beteen Amsterdam and The Hague. It's a very lively place, with good leiden,nightlife:nightlife and many nice leiden,eating out:restaurants.
Main attractions are the Museum of Antiquities with an excellent collection of artifacts from Egypt, Greece and Rome, the Hortus Botanicus one of the oldest botanical garens in the world, planted in 1578 and the Pieterskerk with the tomb of John Robinson, leader of the Pilgrim Fathers. Most of the sights are very close to each other, on or near the Rapenburg, a major canal in the centre.