La Granja de San Ildefonso is a small town about 15 km southeast of Segovia, built around the Royal Palace that Felipe V commissioned in 1720 as a retreat from Madrid. The palace follows the classical French model — Felipe was a Bourbon, grandson of Louis XIV — and the gardens are the real attraction: elaborate fountains, clipped hedges, and long avenues of trees that make it Spain's answer to Versailles.
The fountains run on gravity-fed water from the mountains above and are only turned on for special occasions, so check the schedule before visiting. Inside, the palace has a surprising collection of Flemish tapestries. The town itself is quiet and pleasant, with a couple of good restaurants and a glass factory that has been operating since the 18th century. The Sierra de Guadarrama rises directly above town, offering excellent hiking in summer and skiing in winter.