Yes there are many taxi's about during the day, much less after midnight.

There are many taxi's outside the airport during the day when flights are expected to land.

If you are out late at night and there are no taxi's around, call into a hotel reception they should be able to get you a taxi to take you back to your hotel.

If you are walking any distance, be aware that the main roads and many paths are cobbled, the stones may be uneven or missing.