Do a "Ghost Hunters" type invite. Invite them to help prove or disprove the paranormal activity at this location. If you have time do some research on the general area around your location. (visit local historical society or museum) Write something up about it & include old photos if possible. By tying into past local events it makes it much more believable. If you can't find any photos, then fake it with digital recreations & have photos printed in Sepia tone or Black in White. Make their tombstones out of foam to add to the fun. Goto thrift stores & purchase an old wedding gown & suit. They could be proclaimed as the dead couple's wedding clothes. Look for any old antique props to include to be the doomed couple's things. (examples- ornate hairbrush, old camera or typewriter, small mirror)
Make the place look old an abandoned by covering furniture with old plain white sheets. Add faux spider webbing all over the place- light fixtures, mirrors, windows, etc. Keep the lighting as low & dimmed as possible. Place a mixture of battery powered candles (tealight & pillar) along with real candles. Only use real candles in common areas where people will be all the time. Could even place them in a quart mason jar as a small lantern. Wrap a medium weight wire around the lip of the jar & hold in place with the ring lid, to make a holder. Purchase some cheap flashlights as party favors to add to the mystique.
Make the place look old an abandoned by covering furniture with old plain white sheets. Add faux spider webbing all over the place- light fixtures, mirrors, windows, etc. Keep the lighting as low & dimmed as possible. Place a mixture of battery powered candles (tealight & pillar) along with real candles. Only use real candles in common areas where people will be all the time. Could even place them in a quart mason jar as a small lantern. Wrap a medium weight wire around the lip of the jar & hold in place with the ring lid, to make a holder. Purchase some cheap flashlights as party favors to add to the mystique.