Well, this is a list of places you may consider hitting when you are in trivandrum. Apart from just enjoying the fine dining at four stars in and around the city these places will get you know trivandrum and its people the best.
1. Padmanabha swami temple
As far as i can remember, this was the first place that i did visit in trivandrum. Shree padhmanabhaswamy kshetra or the Padmanabha swami temple was not built in kerala temple architecture style, but in dravidian (Tamil) style. The temple has been quoted in hindu puranas and the epic, mahabharatha. The temple was believed to be one amoung 13 holy adobes in malay nadu (Present kerala and few of tamil nadu). There is a lot to read about this temple. You may find a brilliant wiki entry here.
Note: You need to strictly follow the dress code to visit this temple.
2. Trivandrum zoo and napier museum
The zoo and museum is kept neat and tidy as in Indian standards, I would say. The zoo encounters a great volume hit by holidays and in the weekday evenings from casual visitors to tourists as this is the city’s joggers spot and hangout location for city dwellers. I am a fan of the zoo and would love to contribute to it sometime when am rich enough. The zoo has a lot of animals which includes an anaconda, which was lately added. The rates are cheap and you can click your camera if you pay for it. Napier museum, exhibits collections by the royal travancore family and their belongings. This is also a place were you can sit back and relax. Although the museum is located in city, you will find it calm and serene. The gardens and lawns are well maintained.
(Uh, wait let me find my list.)