To help, knowing your era and event building success.
Inno Tower - Lvl 100 (delete)
Cape Canaveral - Lvl 96 (keep)
Hagia Sophia - Lvl 57 (delete)
Temple of Relics - Lvl 32 (I was thinking about deleting mine, but a friend told me to keep it. So that's up to you)
Blue Galaxy - Lvl 10 (keep+level)
Galata Tower - Lvl 17 (Like JBG said, it's so small, I'd just keep it)
Virgo Project - Lvl 12 (Depends on how much fighting you do)
Flying Island - Lvl 12 (delete immediately)
Your event building success is an important factor
1) F2P - you get the full event building but really nothing more, usually place bronze, GBs are more help for this type of player
2) Occasional diamond spender, usually get extras in events, this is actually me. Some events I will spend because I like what is offered, So, GB's lose value
3) Spender, silver or gold league usually - well only the BG matters, the rest you get from event buildings
VIRGO (GONE)
I am PME - I have absolutely no need for a Virgo.
Some in SAT like the Virgo for GE5.
I don't think other ages really need this GB, limited hits, best case, 70% and 5 attempts, I would get rid of it. Large FP investment to get it to be that productive too.
GALATA (GONE)
Small footprint and cheap to level. Is it needed? Goods 3 ages back ME and on, 47% chance, 6 attempts L71, not sure it is worth investing FPs.
HAGIA (BYE BYE invested FPs)
FPs are always nice to get but yours is L57, so if you delete now, no more investment, you would be OK. Mine is 100, harder decision for me when it comes time space is an bigger issue for me. Had I known where Inno was going with event buildings, I would have deleted it before I did the 60 to 100 level march.
FLYING ISLAND and ToR (GONE)
You don't have a lot invested in the FI, to get it good, L60. It gives goods and FPs, CF and Cape, so I would get rid of it. ToR also fits into this category, some goodies from GE, L32 so some investment.
INNO TOWER
L100, I would keep it for now. I am noticing these auxiliary event buildings, like the recent winter spa, need population. There should be plenty from event buildings, even if you are #1, F2P. I would delete the above first, then see where things are going with the game.
CAPE
I am on the KEEP IT side of the fence, 96 FP guaranteed, would be very hard for me to delete.
BG STAYS, get it to 68, doing double dips all the way up, then next stop, L91, same with double dips.