self guided walking tour recommendations for a family of 4?

[E46M3]

girls are 6 and 10 and have no problem walking. After researching for things to do here, I've settled on doing some self guided walking tours for both food and sightseeing. I'd like to see some castles, historical sites, culture and food. Any good self guided maps I can just download that are good for us? And is it safe and use common sense kinda thing? Thanks! 

[crewsweeper]

First...No castles.   Castillos are forts.  Look up the Paseo Princess walk on this forum or the web.  Also lots of walking tours.  El Morro is a great stop.  Buy a cheap kite at CVS near the pier and fly it on the expansive grounds there.  There are a number of museums, Your children may like Museo del Ninos

Be sure to get a piragua (shaved ice) from one of the vendors in the squares.

Lots of places for good lunches.  Recommend Raices, La Mallorquina or El Asador for good Puerto Rican food and reasonably low prices.  Also Cafe Mallorca for good bakery items., including name sake.

See other attractions here. Kid Friendly Old San Juan | Discovering Puerto Rico.