Galle, like the rest of Sri Lanka, is a safe place for tourists to visit.
You would need to be extremely unlucky, reckless or foolish to experience misfortune.
However, it is your responsibility to exercise due care and caution.
Climbing the Ramparts
The climb to the rampart pathway is easy. There are a number of locations on Rampart Road and elsewhere with good access.
There are no restriction on actually clambering up on to the top of the fortress wall. It is fun but you do so at your risk! A strong gust of wide or if you loose your balance could result in a nasty fall of up to 20 meters and possibly death.
It is best to use only bottled water for anything that goes into your mouth. That includes drinking, brushing your teeth, etc.
Don't forget to keep your mouth shut when in the shower. Lots of people forget this.
Western stomachs aren't used to Eastern bugs. This is a fact of life. So be careful.
If you pig-out on your first day in Sri Lanka and even worse if you eat uncooked, or unwashed or food from a street vendor, well you are asking for it. Over time your tummy will adjust and you can be more and more adventurous.
Most reputable establishments within the Fort and 5 star hotels and restaurants in particular have very good standards of hygiene. They are safe to eat in.
If you have a sensitive stomach, avoid uncooked food and unwashed fruit. Drink only bottled water.
If you get sick the local hotel doctor will fix you up in a flash. They usually know exactly what your aliment is and how to fix it (cost around $50 with medication). If you have your own anti-diarrhea medication that will work too but probably more slowly that what the doctor gives you.
Depending on how well you have acclimatized yourself you may sweat profusely in the hot and humid weather. Be sure to take a bottle of water and keep yourself hydrated.
There are plenty of places to stop, relax, cool down and have a drink.
Any sort of physical harm is very, very unlikely.
A female alone will draw attention from young men. Unfortunately, this phenomenon in not unique to Sri Lanka. The best precaution is to travel with a companion, stick to reputable hotels and venues and ignore the attention. Don't talk to them that will only encourage them. Never accept any offers from strangers.
Theft, Touts, Con-artists & Bamboozlers
Galle is very safe but just like any other place on earth unwitting travelers are easy targets for criminals. Be watchful of your belonging. Don't flaunt your wealth or wads of cash. Hold your belongings close to you.
Galle isn't immune from touts, con-artists and bamboozlers. These characters will try to befriend you with a friendly smile and ask you where you are from to strike up a conversation with you. Never be conned by sob stories or offers of fantastic prices on precious gems or special deals. Ignore these people or politely and firmly say "No Thank You" eventually they will leave you alone. Here are some well-known Scams, Fraudsters and Touts.