Laser Magic--Future City. Cool if you're in the mood, or can get yourself in the mood for a laser son et lumiere spectacular. Hayden Planetarium, Museum of Science, Friday at 9:30, 10:45, Saturday at 5:30, 7, 8:15, 9:30 and 10:45.

Boston By Foot--size 10 and up (men's) only this weekend. A great way to get to know something about the Hub or Beacon Hill. Saturday at 10 a.m., Sunday at 2. Call 367-2345.

Boston Harbor Islands--Mass Audobon Society shows you nature at its finest (?) on the harbor islands, or what's left of them. Saturday tour, call 696-0920.

Bastille Day--is today, kids, and the French Library at 53 Malborough Street, Boston, will boogie down in the street tonight. Call 266-4351.