Charlestown has two Orange Line MBTA stops, Community College and Sullivan Square.  It also has two MBTA bus lines, the 92 on Main St. and the 93 on Bunker Hill St.  There are two MBTA water shuttles, the Charlestown Navy Yard to Long Wharf and the Charlestown Navy Yard to Lovejoy.  You can walk it from the Navy Yard across the bridge to the North End and the Financial District in 10 to 30 minutes, depending on how far you go.  And you can drive in from Exit 25 (Causeway St./North Station) and Exit 28 (Charlestown/Sullivan Square) on Route I-93, the Charlestown/Somerville Exit on Route 1 after the Tobin Bridge, Storrow Drive in Boston or Memorial Drive in Cambridge.

Subway
Orange Line

Bus Lines
Route 92
Route 93

Water Shuttle
Long Wharf/Charlestown
Lovejoy/Charlestown Navy Yard