First, its architectural highlights include the new classicist Stadhuis and the Koornbrug (currently under renovation) but also an old castle, the Burght, which offers a nice view of the town. Walking around in the city center with its characteristic cobblestones, you see one beautiful building after another. Try the areas around the Pieterskerk and the Hooghlandse Kerk, where you find hofjes –private courtyard areas with small houses, usually around a garden. There are about 35 in the city to find using this walk: http://members.chello.nl/m.klein5/walking along the hofjes of Leiden.htm.
Next, the museums. There are over 12 of them in Leiden. The Boerhaave Museum deals with the history of medicine; Naturalis is the National Natural History Museum (very good for kids). If it’s art you’re after, try the Lakenhal; and for Roman and Greek art, go to the National Museum of Antiquities. For anthropological artifacts, there is the National Museum for Cultural Anthropology. The city’s hospital houses the (rather small) Anatomical Museum, which has a cute orchestra with mouse skeletons as a highlight. Not really a museum, but extraordinarily beautiful is the Hortus Botanicus, the oldest botanical garden in the Netherlands, and home to literally millions of plants.
Of course, as a university city, eating can be done in one of the many cafés and restaurants for a reasonable price. Try the ones on the Nieuwe Rijn, as most of them have terrace boats so you can eat on the water.
As for shopping, Leiden’s stores are comparable to Enschede. The Breestraat and the Haarlemmerstraat are the most important shopping areas.
For more information, check the tourist information website: http://www.hollandrijnland.nl