San Cristóbal's strangest sight, currently used as the National Penitentiary School, was built on Trujillo’s orders for himself and his family in 1947 (at a cost of US$3 million), but he reportedly hated the finished product and never spent a single night there. The name means ‘Castle on the Hill,’ which is pretty accurate – it overlooks the city – but the concrete-and-glass structure looks more like a Miami office building than a castle.
Inside, however, huge dining rooms, ballrooms and bedrooms have ornate neoclassical ceilings and wall decorations. The bathrooms – of which there must be 20 – have tile mosaics in reds, blues and gold leaf. There are six floors in all, and you can spend half an hour or more just wandering through the once-abandoned structure. There's also a small museum dedicated to the Dominican Penitentiary System, featuring a few original instruments of torture and murder, a replica electric chair and – huh? – loads of exquisite bed frames. All visitors are escorted by businesslike National Penitentiary School employees.
Any taxi driver or motoconchista (motorcycle taxi driver) can take you there – it probably makes sense to ask the driver to come back in 30 to 60 minutes to pick you up. To get here yourself: from Parque Independencia take Calle María Trinidad Sánchez west for 700m; take a left onto Calle Luperón and follow it up the hill 500m until you reach a fork in the road; veer right and head up the hill another 700m to the entrance gates. Visitors must adhere to the dress code of shirts and closed-toe shoes.