I simply want to know if swords are legal to own in Baltimore, MD.

The main issues involve the POSSESSION, not ownership of weaponry, particularly out of doors and/or in concealed state. Switchblade knifes - i.e. a knife with a blade that ejects or folds out by means of a spring - are generally illegal to sell, display for sale transfer or conceal anywhere in Maryland (Md. Ann. Code Criminal article section 4-101), are illegal to possess at night in many jurisdictions in MD. Switchblades are totally illegal to possess EVER in Baltimore City under Baltimore City Code section 59-22 ("Weapons"). Don't own one or if you do, store it lawfully in a secure locker or safe outside the City and never transport it through or into the City. However, a fixed blade sword that is carried openly or simply owned in your home is not prohibited in itself because its blade is not spring operated. Please consult legal counsel if you are a collector. I don't actually know whether it's "illegal" to bring a scabbarded sword fully disclosed onto the places you mentioned though the property owner has the right to have you thrown out and charged for trespassing if you violate policy. However, you should definitely act as if it were illegal or get advance written permission to bring such an item onto such places (and why would you except possibly for a Hallowe'en party?) I am certain that many military bases have swords for decorative use in parades by properly uniformed enlisted and or commissioned servicemembers but that would certainly not apply to a collector.