Matanzas has a very compact city center, and a few hours of walking around are generally enough to get a good feel for the place. There are two small plazas that anchor the social and cultural life of Matanzas, the Plaza de la Vigía and the Plaza de la Libertad. Both are within 5 blocks of each other in Reparto Matanzas, the central section of the city.
Probably the most visited site in Matanzas is the stunning neoclassical Teatro Sauto, on the Plaza de la Vigía (tel. 45/24-2721). The theater, which was finished in 1863, is the design of Italian architect and artist Daniel Dal'Aglio, who also painted the beautiful frescoes that adorn the ceiling. Dance, theater, and classical music performances are still regularly held here, and it's worth checking to see if there's anything playing while you're in town. Otherwise, you may be able to take a guided tour of the theater; CUC$2 between 9am and 5pm daily.
The other main attraction in town is the Museo Farmacéutico, Calle 83 no. 4951, Plaza de la Libertad (tel. 45/24-3179). Seemingly little has changed here since its founding in 1882 by the French pharmacist Ernesto Troilet. Porcelain jars of potions and elixirs are stacked high in beautiful floor-to-ceiling wood cabinets. The museum is open daily from Monday to Saturday 10am to 5pm and on Sunday from 10am to 2pm; admission is CUC$3.
At the head of the harbor, close to the downtown center, you'll find a couple of small stretches of beach, where there will almost always be a few locals swimming, fishing, and sunbathing. However, the harbor is quite industrial and I'd highly recommend you head over to Varadero for some more inviting beaches.
Out on the northern edge of the bay is the Castillo de San Severino, Avenida del Muelle. Built in 1734, this small fort served as a line of defense, slave-trading post, and long-standing prison. It's been restored and is definitely worth a visit, if for nothing other than the great view of Matanzas Bay. The Castillo is open Mon-Sat 9am-5pm and Sun 9am-1pm; admission is CUC$2.
On the outskirts of the city, you'll find the Cuevas de Bellamar, Finca La Alcancia (tel. 45/26-1683), a cave complex of nearly 3km (1 3/4 miles) of galleries and passageways, with intricate stalactite and stalagmite formations, indigenous pictographs, and several underground streams and rivers. You can tour the first kilometer or so of caves for CUC$5 per person, including a guide. This section is lit, so no equipment or flashlights are needed. The caves are located 5km (3 miles) southeast of Matanzas, off a well-marked access road. They are open daily from 9:30am to 4:15pm.
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.