This is a Passion flower, Passiflora species. The flower has an unusual arrangement as the carpels/fruit are above the male reproductive organs, the stamens.
From the top of the flower the three round structures at the upper most part are the three stigmas, the female reproductive organs. The pale green oval they are attached to below will develop into the fruit once fertilised. Below this are the five stamens which produce the pollen. All the reproductive organs are hanging face down towards the centre of the flower where the nectar is produced, the pollen will get dusted on the back of the head of the pollinator and then brushed off onto the female stigmas once they become receptive.
The rings of filaments between these and the petals are novel organs seen in Passiflora and a few other genera. The nectar is produced from a ring of tissue below these. Then the five red petals and finally five red sepals - structures which enclose the flower in bud and protect is against damage as the flowers develop.
This flower could well be pollinated by birds as they tend to prefer large, red flowers.
I hope this is of interest to you...