Old Havana is a great place, take a walk in the small streets, enjoy the people around and the music you'll hear from everywhere, Have a drink in the small cafes / Bars or lunch in one of the restaurant, enjoy the book market and all the amazing architecture of all the surrounding buildings. When you go to the bars, try the famouse drinks of cubaThe Mojito ! ask the barmens for the best local drinks, they will gladly recommend.
Havana is separated into two sections: Old Havana and New Havana. If you go to Old Havana, you'll see the castle where they used to protect the city from. Ships filled with raiders used to come into the harbour at this point, and loot the city. To stop this, Cuba created a big castle here, complete with cannons to protect the city.
A few historical buildings are very well mantained and can be safely visited. The Plaza de Armas with the peculiar wooded pavement, the monument to Antonio De Cespedes and the book stalls is one of the most charming place. You may also experience a scroll up and down Paseo, from the Garcia Lorca theatre to Malecon, on the sea-front.
Go walking around Habana Vieja. Lots of ancient building are under repair, but, unfortunately, money is not enough, so that in many cases these are just superfical external repairs. They won't last, and every summer storm is causing severe damages to the buildings.
This 16th century square is surrounded by elegant colonial buildings as well as early 20th century art nouveau ones.
I think there are a lot off tips here on VT about visiting Havana Vieja, I can only add some of my pictures I made there.
\Havana Vieja is such an arty place, just hanging around u bump into all these art markets, special exhibitation, various patios with modern paintings and sculptures...lovely
Having a walk around Old Havana is a must. The museums are worth the visit and it's also nice to just chill at a bar drinking mojito and getting entertained by the street perforners...
If you wander by Havana Vieja and you are a book lover, you have to go to the Plaza de Armas. (I don't know if this is permanent) Old books are for selling there by people in a book market.
Please, if you come to this wonderful city, just take some time out and walk. It is such a great place, and the people are so friendly.
The buildings are amazing
Baseball - the national sport - played by children - near the famous Malecon - somewhere in the streets - in ruined and to be renovated places in Old Habana
La Habana Veja: in this old part of Havana there are many buildings in Spanish style. If you look beyond the main entrance you can see these cool open courtyards with a balcony all around.