
It can be easily concluded that how strong the architecture of that age was. In this modern technology age where we have several modern equipments available we cannot even think of making such type of bridges.
Now it's a question worth million dollar that where did such a intense thinking about architecture design gone? I think that, technology should improve as the time passes and we should be able to make better architectures. Now if we see that Rama's bridge was made 1,750,000 years ago, so after 1,750,000 we should be able to at least make a bridge on say Pacific Ocean. But that is not the case.
Also if we consider this epic (Ramayana) true (on the grounds of Rama's Bridge) then in Ramayana, there was a aerial car (known as Pushpak Viman) that travels with the speed of mind and it was able to grow large and small at a wish. Now in this modern age we are able to make aerial car but still it cannot fly with the speed of mind, so we are lacking in technology compared to that age's technology.
At this point my only question is "where has all that technological thinking gone?"