I had visited many times at jantar mantar with my freinds and family but this palace is not expected to visit because it have a heart shape structure which is not much interesting and garden premises around it as usual so my suggestion for you all guys it is not good palace to visit but if you really want to visit so you can visit easily at qutub minar which is more interesting than jantar mantar and it is much near of jantar mantar so you can visit easily.qutub minar is best choice of alternative between qutub minar and jantar mantar and ofcourse delhi knows a great city which is famous for visiting its many famous palaces like - india gate , qutub minar , akshardhaam , lotus temple , iskon temple , red fort , humanyun tomb , deer park etc. Which is most attractive places than jantar mantar so should visited there if u had not visited my personal advice for you guys jantar mantar is not to good palace for visiting according to me.i live in delhi so I know about delhi very well.