There is not much to see in Puerta de Tierra, but there are a few things of interest for the traveler looking around this area. Old San Juan is a 25 minute beachfront walk away; walk along Avenida Munoz Rivera until you reach San Cristobal fort, then turn towards the waterfront on Calle de Norzagaray.
Casa de Espana
Avenida Juan Ponce de León. Walking distance from Old San Juan, this house is literally something to see, as the average tourist cannot go in unless they are involved with one of the many events hosted there. Still, the building, which gets its name from its original purpose as a community center for local Spanish citizens, is worth a look for its architectural accents and 'old world' look. It is closer to Old San Juan than the hotels of Puerta de Tierra, but it is on the bus line. Coming into Covadonga bus station, look to your right when the bus is on Paseo de Covadonga. It will be on the next street over, but you can see it from the bus window. There is a sign out front that marks the building.