Santiago is a large sprawling city nestled right up against the foothills of the Andes.
On a clear day you see the snowcapped 5,000m+ peaks towering overhead. The colonial parts of the city now form the downtown shopping area. At the heart of it all is the pedestrianised Alameda (main avenue) leading to the Plaza Mayor with its imposing cathedral.
A stroll along the Alameda is generally a lively and fun experience. Artists are usually painting in the main square, buskers playing and even dancers.
You should be careful of pickpockets but other than that, Santiago is a generally safe and relaxing place to explore.
At night you will find that the downtown area is less inviting.
The best areas at night is Providencia with its bars and restaurants and busy streets. Las Condes is an even nicer neighbourhood further east (towards the mountains) though things tend to be more spaced out and less walkable than is the case in Providencia.
Also a good option at night is the Bellavista neighbourhood, across the river a the bottom of the Cerro Santa Lucia.
This is a pretty, low rise, cobbled colonial neighbourhood of bars and restaurants and galleries. It is much earthier than Providencia but has got some superb places to eat.
In broad terms you might like to think of Bellavista for diner and Providencia for going out for a drink later in the evening.
The centre as far as the Cerro Santa Lucia is a pleasant place to stroll during the day and can be easily combined with a visit to the lively Bellavista quarter with art galleries, jewellery shops as well as good restaurants.
The mercado central, a few blocks north of the centre, is a lively and colourful food market. Nearby are museums dedicated to Fine Arts and Pre-Colombian art which are both well worth a visit.
The Iglesia San Francisco on the main drag is the oldest in town and worth a quick visit. On your way to the Pre-colombian art museum, swing by the Moneda palace.
From the museum you can make your way across the busy Plaza de Armas to the Mercado Central for lunch before returning via the Cerro Santa Lucia for an afternoon view across the city to the mountains.
To get up onto the higher hill, take the metro to Baquedano and cross the river towards the foot of the Cerro San Cristobal.
Walk up Pio Nono through the Bellavista neighbourhood with its many gift shops.
At the foot of the hill you can either take the funicular or a collectivo (shared) taxi for about 500 pesos (50 pence).
On a good day you can see the Andes. They are only 20 miles away but the pollution often obscures the view entirely.