Most attractions in Old San Juan, Puerto Rico (PR) are within walking distances to each other...the reason why a walking tour is highly recommended. Wearing your most comfortable shoes is also highly suggested mostly because the streets are partly hilly and are paved with cobblestones.
Streets are narrow and can be steep at times particularly when the streets get wet. Cobblestones that are on the streets are actually cobbles of adoquine, - a blue stone cast from furnace slag. These stones were brought by Spanish ships and they got their colorful characterisitc due to time and moisture.
Old San Juan is considered to be a 465-year old community, used to be a military stronghold and ultimately transformed into a commercial and charming, residential district. These are more than 400 16th-17th century Spanish colonial buildings carefully restored in the city of San Juan. Old San Juan brings many tourists each year enjoying fine beaches, casinos and its tropical climate.
If you are visiting Old San Juan by foot, it can also be challenging experiencing the heat, mostly in mid-late afternoons. During spring, summer and fall, walking can sometimes become a bit oppressive due to heat, with crowded, tall buildings blocking the breeze. Good options to do in order to avoid the heat of the tropical sun and humidity would be to start the walk early, as most stores open at 10AM during weekdays, or you can consider catching up trolleys for free that goes back and forth throughout the area, and get the chance to get off at marked stops wherever you desire.
Have a fun-filled visit! ;)