At the north end of the Habana Vieja is the Plaza 13 de Marzo, a simple public park dominated on it's southern end by the spectacular building which houses the Museum of the Revolution, by far Havana's most popular attraction.
The ornate presidential palace was completed in 1920 and was home of the President of the republic from then until the revolution, and it is by far the most impressive building in the whole of Cuba. The interiors are truly sumptuous and a couple have been preserved in their original state, including Batista's office from which he fled at the approach of Castro's troops and a hall decorated by Tiffany's of New York. Out front you can also see one of the last remaining chunks of the old city wall and the Tank that Fidel rode in when repelling the Bay of Pigs invasion in 1961.
The museum (admission $3) is a fairly standard telling of the story of the revolution from its early underground days all the way through to the modern day successes through the medium of documents, photographs, models of battles and personal belongings of the revolutionaries. The story is an interesting one full of adventure and excitement and seems to have been very well documented with surprisingly fine photographs of a movement that was supposed to be underground. Some of the individual stories are moving and even the tacky wax models of Cienfuego and Che manage to tug at the heartstrings.
Behind the palace is The Granma Memorial a large glass pavilion which houses the Granma, this was the boat that Fidel, Che and their companions first made land fall in Cuba onboard, having traveled across from Mexico. The boat has gone on to become a venerated symbol of the revolution, but it is in itself far from impressive and the pavilion makes it very difficult to get a good look at it. Dotted around the pavilion are various vehicles and remains of vehicles that were used in the revolution and the Bay of Pigs invasion, highlights include the remains of a US B-26 shot down by Castro and a home made tank used by Cienfuego.
On your way out don't miss the Cretins, one of the few exhibits in English, it consists of charicetures of Batista, Regan and Bush thanking each one of them for their contributions to the revolution. It is one of the more obvious examples of the mix of fact and propaganda that makes this a highlight of any visit to Havana.