Physicians and scientists inclined to a busman’s holiday might walk one block west and one north of Plaza Vieja the plaza and check out the Museo Histórico de las Ciencias Naturales Carlos Finlay (Museum of Natural History, Cuba #460, e/ Amargura y Brasil, tel. 07/863-4824, Mon.–Fri. 9 a.m.–5 p.m., Sat. 9 a.m.–3 p.m., CUC2). Dating from 1868 and once the headquarters of the Academy of Medical, Physical, and Natural Sciences, today the Museum of Natural History contains a pharmaceutical collection and tells the tales of Cuban scientists’ discoveries and innovations.

The Cuban scientist Dr. Finlay is honored, of course; it was he who on August 14, 1881, discovered that yellow fever is transmitted by the Aedes aegipti mosquito. The museum also contains a medical library and, on the third floor, a reconstructed period pharmacy. It has a rooftop bar with a good view of the harbor.

Adjoining the Museum of Natural History to the north, the Convento y Iglesia de San Francisco el Nuevo (Cuba, esq. Amargura, tel. 07/861-8490, Mon.–Thurs. 9 a.m.–6 p.m., Sun. 8 a.m.–1 p.m., free) was completed in 1633 for the Augustine friars. It was consecrated anew in 1842, when it was given to the Franciscans, who then rebuilt it in renaissance style in 1847. The church has a marvelous domed altar and nave.