Built in 1832 and enlarged in 1909, this stately, granite-domed edifice was designed by Charles Bulfinch (the Boston architect behind the nation’s Capitol building in Washington, DC). Walk-in visitors are welcome; you can pick up a leaflet for a self-guided tour or join a free guided tour (hourly from 9am to noon).
Highlights include a curious butterfly and moth collection in the Welcome Center (the first room to the right after the security screening), the 3rd-floor Senate and House voting chambers, the views over wooded Capitol Park from the 3rd-floor terrace (rocking chairs provided), and artist Klir Beck's wonderful animal dioramas capturing Maine's four seasons (these are hidden in the Underground Connector – head down the stairwell just before security).
You can park in the lot on the southwest side of the building, near the Department of Education and the Maine State Museum, and enter the capitol through the southwest door.