The gardens boast great views of central KL, as well as having boats for hire and a small equestrian track (Sat-Sun/public holidays only) where you can go horseriding or take a ride in a horse-drawn carriage.
Titiwangsa has both an LRT and Monorail stop, but these are an unpleasant walk to the gardens.
Another possibility is RapidKL Bus B103 from KLCC -- the nearest stop is opposite the National Cultural Centre (ask for Istana Budaya). All in all, the best option is to take a taxi.
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