SOUTH PORTLAND — The hotel across the street from the Maine Mall is undergoing a renovation and will change its national affiliation.

The hotel, with two circular buildings, is currently a Wyndham hotel, but it will become a Doubletree by Hilton hotel by the end of the month.

The renovations, expected to cost about $3.7 million, included a change to the exterior, which was originally all glass. The new exterior features new textures and colors, a press release issued by the hotel said.

The hotel’s restaurant, Blue Wave Grill, is also being redone, and room upgrades include high-bandwidth wi-fi, new TVs and bedding and new heating and cooling units. The fitness room is also being redesigned and a lounge for Hilton Honors members is being added.