Ozzie D, NP-hard 
The #BowTieRide route starts in mid-Cambridge at Joan Lorentz Park, in front of the main branch of the Cambridge Public Library. It heads east on Cambridge St, Hampshire St, and Bristol St, then doglegs left (N) up Fulkerson St, right (E) on Charles St, left (N) on Third St, right (E) on Thorndike St, right (S) on First St, and a right (W) onto Broad Canal Boardwalk (turning into Broad Canal Way). It doglegs left (S) on Third St, turns right (W) on Main St, left (SW) on Sidney St, right (NW) on Hamilton St, left (SW) on Pearl St in the Port, right (NW) on Chestnut St, doglegs right on Pleasant St and left to Putnam Ave, turns left (W) on Western Ave, and then stops at Riverside Park for a break.
The route continues west along the river on Memorial Drive, turns right (north) onto JFK St, does a series of little maneuvers to avoid Harvard Sq (Elliott St to Mt Auburn St), turns right on Hilliard, left on Brattle, and continues to wend west on Brattle St thru Old Cambridge, until turning right on Lakeview Ave and heading north through Huron Village. It then takes a sharp right turn (E) onto Vassal Lane, a left (N) onto Walden St, a left (W) onto Fayerweather St, which continues onto Field St, and then bends left onto Bay State Rd, which terminates at New St (just before one of the Concord Ave rotaries, aka the Double Donuts of Doom). However the route takes a sharp RIGHT (N) onto New St, and then turns into Danehy Park (erstwhile landfill), passes multiple soccer fields, native gardens, and softball fields--
including my daughter's team playing 10U softball against Winchester (GO CARDINALS)--
then dumps out onto Sherman. The route turns right on Sherman St, left (W) again on Walden St, right (SE) onto Raymond St, left (NE) onto Linnaean St, continuing until it T's with Mass Ave. It turns right on Mass Ave, then immediately left (W) on Garfield, and shortly thereafter turns right onto Oxford. It heads south on Oxford St towards Harvard Sq, turns left (E) onto Kirkland St, then turns right (S) onto Irving St, until it meets Cambridge St at the Cambridge Rindge and Latin campus -- where it meets its end. If you read this far, I apologize, and if you rode this far, I salute you.