Halloween falls on a Tuesday this year, meaning the weekend leading up to the holiday will be packed with costume parties, bar crawls and kid-friendly activities. But Halloween is much more than one night, or even one weekend — these days, you get at least 12 days of celebrations, if not more, and our calendar is already packed with film screenings, costume parties, canine costume parades, pumpkin painting and author talks. But this weekend brings much more, including Howard University’s legendary Homecoming Yardfest, tours of dozens of Loudoun County farms, an international celebration for families, a Harry Potter film festival and a celebration of hip-hop’s golden anniversary.