You're going to need to specific about a place/period or fortification system. Even then, I may not know the technical works. For an overview of Roman forts, Luttwak, Grand Strategy of the Roman Empire has a good cross-period comparison for a newcomer to the topic.
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For Bastion forts, I'd suggest just going to one. There are several well-preserved small forts in the USA (McHenry being the most famous; Fort Moultrie in Charleston has a fascinating design that divides the fort by eras, from 1776 to 1947).
If you are in Europe...well, you have a *wealth* of options for well-preserved bastion fortress complexes. I haven't made a trip to Europe yet that hasn't involved at least one bastion fort, often in surprisingly good condition.